meaning of chmod command in linux code example

Example 1: chmod

chmod u=rwx,g=rx,o=r myfile

chmod 754 myfile

# 4 stands for "read",
# 2 stands for "write",
# 1 stands for "execute", and
# 0 stands for "no permission."

Example 2: chmod

For changing permissions mode of files as "file.exe" follow next examples idea:
chmod file.exe ugo+x #Add x:execute permissions to u:user g:gropu and o:others
chmod file.exe o-rw  #Remove r:read and w:write permissions to o:others
chmod file.exe +rwx  #Add all r:read, w:wirte and x:execute permissions to all.