That person standing over there is my brother.
Please stand on the stone.
The person standing over there is your future child.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means "stand" so what is the verb version of that? It's to stand.
Don't confuse this with 立てる, which means "to stand something up." 立つ isn't an action you do to something else. It's "to stand" as in "she's standing over there" or "stand up now!"
You have to remember the た portion of this word to learn the reading of it. Think of it this way:
You have to stand up in order to wave goodbye to someone. When you stand up, you also say ta ta (た)!