Meaning of “log in/on” - Learner’s Dictionary

log in/on

phrasal verb with log uk us /lɒɡ/ verb [ T ] (present participle logging, past tense and past participle logged)

B2 to connect a computer to a system of computers by typing your name and often a password, usually so that you can start working

(Definition of “log in/on” from the Cambridge Learner’s Dictionary © Cambridge University Press)