Hi there and welcome !
First try and boot into single user mode...
You can start up the Mac and hold down the command + s keys...untill you get to a "prompt"
Then type
/sbin/fsck -fy
then press return
This will manually run FSCK...then once it has finished (it may take a while) type
reboot
and press return.
If it still gives the same messages then boot into Single User Mode, mount the drive and delete a few files...I'll explain this later if you are not sure how to do it...
regards
Ric