These are called the principal parts of the verb. They're the same verb, but in different forms.
Basically, one form isn't enough to know how to use a verb properly. Imagine if you didn't know English, and looked up the verb give in a dictionary. From that one form, how would you know the past tense? You'd probably guess *gived, but that would be wrong. How are you supposed to know it's actually gave?
So English verbs have three principal parts: if you look up give in a dictionary for English-learners, it'll list these parts as give, gave, given. From these three forms, you can create all the other forms you might need: he will give, I have given, you are giving, and so on.
Latin has these same three principal parts: dare means "give", dedī means "gave", and datum means "given". But there's a slight oddity in Latin that means you need one extra form as well: dō specifically means "I give", because that one sometimes looks different from what you'd expect. So those are the four forms every dictionary will list.
(P.S. Sometimes verbs won't have all these forms; you'll see some verbs listed with only three, or some with only two. This generally means certain forms are unattested: they've never been seen "in the wild", and are assumed not to exist. For example, meminī, meminisse, "remember", only appears in the past tense. A good dictionary will also explain which forms are missing and how to work around that.)