This little word can be used in many ways. Here are some examples:
"da" means "because" and is often used at the beginning of sentences when we're not supposed to use "weil", like in "Da es regnet, nehme ich meinen Regenschirm mit." (Since it's raining, I'm going to take my umbrella.) This is similar to English and replacing "because" with "since" or "as", especially at the beginning of the sentence.
"da" can also mean "here" or "present", e.g.: "Ich bin da." (I'm here/ I'm present)
"da" can also be used to say "there" or "over there", like in: "Wo ist das Buch? Es ist da drüben." (Where's the book. It's over there.)
But you can also see "da" being used as a filler word, like iin: "Naja, da kann man nichts machen." (Well, there's nothing you can do.)
