This is the 968th most frequent Estonian word.
tal
The Estonian word "tal" means "to him/her/it" (third person singular dative form).
Here, 'tal' is used as the third person singular possessive form to indicate that the person owns the plan.
Tal on plaan minna mägedesse.
He/she has a plan to go to the mountains.
In this context, 'tal' is used to describe a state affecting the person, indicating who is cold.
Tal on külm, ta otsib sooja.
He/she is cold, he/she is looking for warmth.
Here, 'tal' is used as an indirect object pronoun in the dative case specifying to whom the teacher spoke.