1. to (choose to) do something/undertake a task or project
take on responsibilities/a new role/a challenge
This can be used in both a social and professional context. This phrasal verb can mean to 'undertake something'. "I don't know how we're going to deliver this on time. We've taken on a lot of work!" It can also mean to 'hire' or 'to recruit' someone. "I think we need to take someone on to help us with this extra work." To 'take on' can also mean to 'compete against an opponent'. "We need to take on the competition." "How do you feel about taking on such a famous opponent?" It can also mean to 'begin to have a characteristic or appearance of something or someone', "She took on a low tone and spoke secretly."
2. employ or hire
take on a freelancer/new member of staff
'To take on' can mean to 'hire' or 'to recruit' someone. "I think we need to take someone on to help us with this extra work."