Ji is relfexive, yes?
Correct, -ji- is the reflexive infix. The verb kufunza is a somewhat outdated word meaning to teach or to educate. Therefore the literal translation is "I teach myself" = "I learn"!
Just a little nitpick ... -ji- is not actually an infix. Swahili doesn't have true infixes. It's just a prefix that always comes after other prefixes. An infix comes in the middle of a morpheme (a part of a word), not between other morphemes.