It'd be interesting to know even for Russian speakers that there are words in Russian which starts from the letter "Ы".
These words often relate to geographical names of Yakutiya (Yakutiya or Sakha Republic is a federal subject of Russia in the Far East).
1) Ыгыатта (It's a river in the west of Yakutiya)
2) Ыллымах (It's a small rural locality)
3) Ытык-кюёль (It's a rural locality and it's also the administrative center of Tattinsky District of Yakutiya)
4) Ыт-Юрях (It's a river in Yakutiya)
In Russian there are paronyms (words which have a resembling pronunciation but different meaning) that sometimes can be difficult even for native speakers. People can mix them up and using of these words become wrong in conversation.
1) Невежда and невежа. The first word невежда means an ignorant person. The second word невежа means a rude person.
2) Адресат and адреса́нт. The first word адресат means a person who recieve a letter or a parcel. The second word адресант means a person who send a letter or a parcel.
3) Поступок and проступок. The first word поступок means an act. The second word проступок means a bad act.
4) Бал and балл. The first word бал means a ball (a large formal occasion where people dance). The second word балл means a mark or a grade (a judgment, expressed as a number or letter, about the quality of a piece of work done at school, college, or university).
There are many homonyms in Russian (words having the same spelling but different meanings) which can create difficulties for foreigners.
1) За́мок and замо́к. You can notice that the stress of these words is different. The first word за́мок means a castle. The second word замо́к means a lock.
2)The word месяц can mean a month. At the same time it can mean a moon.
Sometimes homonyms can be sentences and we can define the meaning of them only if we see a text.
3) "Мы же на ты!" and "мы женаты". People say the first phrase "Мы же на ты!" when they want to speak more informal (In Russian like in romance languages there is a difference between genders for pronouns. So if we use an analogy with the French language for instance it would be like this: ты - tu and вы - vous). The second phrase "мы женаты" means "we are married".
4) "Несуразные вещи" and "несу разные вещи". The first phrase "Несуразные вещи" means "preposterous things" or "foolish things". The second phrase "несу разные вещи" means "I'm bringing different things".
In Russian you can find archaisms. These are the words which ain't used any more. But you can hear them from old people sometimes or you can find them reading classical literature.
1) Авось - it's an old word which means perhaps, may be. Now people usually use the synonyms возможно, может быть, вероятно.
2) Око - it's an old word which means eye. If you want to say plural variant of this word it'll be очи (eyes). Now people say глаз.
3) Рать - it's an old word which means army. Now people usually say the words армия or войска.
4) Яства - it's an old word which means food. Now people say еда.
Of course together with archaisms there are many neologisms in russian. These are new words which you can often hear nowadays. Many of them have anglicisms.
1) Фейк - it's a neologism which comes from the english word fake. So it means lie, deception. If you don't want to use this neologism you can use other russian synonyms like ложь, неправда.
2) Барбер - it's a neologism which comes from the english word barber. So it means barber hairdresser. In the russian language we usually say the word парикмахер.
3) Спойлер - it's a neologism which comes from the english word spoil. People usually use this word when they want to say that some interesting information about movie or computer game for example is revealed in advance. And if you know this information it won't be interesting for you to know continuation.
4) Гуглить - it's a neologism which comes from the english word Google. People usually use this word when they want to find something using google. For example someone can say in russian: надо бы погуглить и найти информация об этом. Translation - it's necessary to use google and find information about it.