$ ls -l
-rw-r-r- 1 user user 0 Nov 18 22:04 myfile
Obviously the time and user/group names will be different when you try it. The size of the file is 0, because touch creates an empty file. -rw-r-r- is the default permissions mode on Debian.
chmod u+x myfile
This command means to add (+) execute (x) permissions for the user (u) who owns the file. Use ls -l to see the effects.
chmod go-r myfile
Here you’ve subtracted (-) read permission (r) from the group (g) owning the file and from everyone else (others, o). Again, use ls -l to verify the effects.
chmod ugo=rx myfile
Here you’ve set (=) user, group, and other permissions to read and execute. This sets permissions to exactly what you’ve specified and unsets any other permissions. So all rx should be set, and all w should be unset. Now, no one can write to the file.
chmod a-x myfile