The big mistake learners make with this sound is to type it at it sounds - 'wa' so IME renders it as わ。You have to remember to type it has 'ha' in order to get the correct hiragana は。The other common error is with ん　particularly in words like こんにちは, konnichiwa where you have two 'nn's next to each other. You have to hit the 'n' key twice to render the first sound - the ん。If you just hit it once, then go on typing the word, you get こにちは　-which is wrong, but I see it a lot from newbies. It is just a keyboarding issue rather than bad 'spelling' but you need to understand how to render the word correctly or you will get into bad habits. My language partners are always asking me 'why can't people who are learning Japanese write こんにちは correctly?'

は is one of the many particles in Japanese, pronounced as wa. Another particle like へ (he) is pronounced as え. The particles don't really have a specific meaning.

For historical reasons, は is pronounced as "wa" only when it is a particle like in "watashi-wa". At one point long ago, it was pronounced as "ha" but evolved over time and the spelling didn't follow this change. Such things often happen in a lot of languages. The particles like は, が, を, へ, で, に, etc are all very important. They are not used by themselves, but in sentences they have very specific meanings. You could even say they are (one of) the most important things in the Japanese language.

Regarding the translation, it is an error to translate は when is a particule, it has no translation, is just a grammatical word to indicate the subject or main topic of the sentence. For example, if you say 私(わたし)は大学(だいがく)へ行(い)きます, the translation is "I go to the university", and the verb "to be" has no relation here.

That's odd because I've learned that は(ha) is a topic marking particle and doesn't represent the verb "to be" in English.