use Samsung monitor with Mac Air

Without knowing more details about your configuration, it's impossible to say.

If you are trying to plug a wired mouse – or a USB receiver for a third-party wireless mouse – into a downstream USB port on the monitor, then you will need to establish an upstream USB link between the monitor and the Mac. This is usually done over a dedicated USB-A or USB-B link, or as part of a USB-C connection. See your monitor manual for details.