age: the age at which someone begins learning a new language affects how easy or difficult it can be. Age can also be an indicator of maturity and can play into language acquisition this way as well.

abilities in primary language will affect second language learning because of transfer of learning. Transfer can be positive most of the time, but can also be negative in certain cases.

working memory

information processing speed

the primary language(s) spoken influences the transfer of learning of a new language. Sometimes this can be helpful or disadvantageous, for example if the languages are similar it can be helpful, however, if they follow very different grammatical or conjugation rules, it can pose an obstacle.

pronunciation and phonology of primary language influence second language learning and transfer

self-esteem

motivation

anxiety