Can a 1 yr old lab be trained further when he only obeys commands like handshake/sit/no.?

since he's going through a teething phase, he likes to chews on the hands as well, although he's obedient, how can i impart more basic training although his potty training are firmly in place. he is my parents dog and i have met him only for 15-16 days on/off but still he recognises me and obeys my commands. also how to train him for outer house walks?