This is the 942nd most frequent French word.
penser
To think.
The verb 'penser' is used with 'à' to indicate that the subject is pondering or considering something.
Je pense à mes vacances d'été.
I am thinking about my summer holidays.
Here, 'penser' is used with 'que' to express an opinion or belief.
Il pense que c'est une bonne idée.
He thinks that it's a good idea.
The word 'penser' indicates a recollection or fond thinking of past events, and it is combined with 'à'.