Intransitive verb and Godan verb
たつ
あそこに立っているのは、ぼくのあにです。
That person standing over there is my brother.
その石の上に立ってください。
Please stand on the stone.
あそこに立っているのが、あなたのみらいの子どもです。
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.
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)!