They all translate to "the". Der is masculine, Die is feminine and plural and Das is neuter. The majority of Nouns in German are masculine, so if you need to guess, guess "der". If a noun ends in -e, it is probably feminine. If a noun ends in -chen, it is always neuter. The German for "girl" is "Mädchen" and is neuter, this confuses a lot of people. You can work out which to use by seeing them used in sentences, (sometimes). If you see "Ich habe ein großes Messer", you can work out that Messer is neuter because "groß-" ends in -es. The same with der and die. There's a lot of rules for knowing which to use, and there's a lot of words to choose from. Don't worry if you get overwhelmed by everything, because there's a lot to learn. Hoffentlich habe ich dich geholfen!

they all mean "the" but refer to the gender of the item, the man is "der mann" the lady is "die frau" neuter is das, "das hotel", masculine "der" feminine "die" and neuter is "das"

thankyou Austin and Niall,, I get it now,, do you have a tips for me to learn a vocabulary in German use those? how can i memorize it easily?

No, there isn't. You have to learn each noun with its article!