Pronouns are words used to replace a noun. This means you do not have to keep using the noun.
You'd sound foolish if you said,
"Daniel met Ági at Deak Ference Ter
metro and Daniel and Ági went to a cafe.
Daniel had tea and Ági had coffee.
Ági's coffee was too hot."
Better would be to say,
"I met Ági at Deak Ference Ter metro
and we went to a cafe.
I had tea and she had coffee.
Hers was too hot."
The emboldened words are pronouns, including one
Of course the italic words are the nouns we have replaced.