Hi agoesz,
Thanks for using Apple Support Communities! We see you have a question about a MacBook Air used for work, and we'd like to help.
Are you referring to an Activation Lock screen? This would mean that the Apple ID used with the Mac before you, was signed in with a different Apple ID, as shown here: Activation Lock for Mac
If this is the case, and you were given the Mac by your employer, you'll want to refer back to who supplied you with the MacBook Air.
If this is not what is happening, please provide some additional info, so the community can help. However, do not include any personal information, as this is a public forum.
Take care!