A:
(I took French classes before as well as used Pimsleur, which this is in the first 15 lessons somewhere) I’m very confident that this sentence should be “J’en pense”, which means I think about it. The pronoun “y” is to signify a place. “J’y vais.” I go there. “Allons-y.” Let’s go there. (Also meaning, “Let’s go!”) Etc. “En” is to signify a thing, whether it is tangible or not. “Tu en mange.” I eat it. “Vous en buvez?” You drink it? If anything, this sentence could more precisely be said as, “Je pense ca.” (With the cedilla.)
B:
That is an interesting question. I will try to clarify that for you.
PENSER can be constructed with 2 prepositions: “de” and “à” - Ce que j’en pense = ce que je pense DE quelque chose ou quelqu’un (mentioned before) = what I think of it/him/her… (and also what I think about it/him/her/them…) - J’y pense = je pense A quelque chose (mentioned before) = I think about it.
So, with that verb, you have understood that EN means DE+ object and Y means A (accented) + object.
PENSER can also be constructed with a direct object (no preposition needed) - je pense ça - je pense la même chose que toi
ALLER is constructed with preposition “à” - j’y vais = je vais là (destination mentioned before) = I am going there
MANGER & BOIRE are constructed with a direct object (countables) or preposition “de” (uncountables) - j’en mange = je mange DU (pain) or DE (la soupe) or DES (pommes) - j’en bois = je bois DU (vin) or DE (l’eau) or DES (bières)
