Unless it's a helical inside that glass casing...What length is it? You can work out the frequency from that. Likely vhf.
Can’t read it... I can make out “WI**SCH*. Maybe. The letters are really unclear and sun damaged.What does the label say?
Now that you've taken it off, is there something which doesn't work?
VHF spare if demasted.
If we presume there is no system on the boat that does not work with the antenna removed you might look for a coax PL259 connector on the end of a cable not connected to anything that is near the back of VHF set. This could indicate a standby or emergency VHF antenna. ol'will