Error #487

Hey, I am new to this today I was learning nmap but when I typed this commad ( nmap -sT -p ) it showed error #487 and said your port specifications are illegal and at the end it said QUITTING!. Can someone explain me what is it.
And I am running Kali Linux on vmare.

The command switch -p starts the specification of a port or a range of ports.

For example scan only TCP port 80:

nmap -sT -p80 localhost

For example scan all TCP ports in the range 10,11,12,…,100:

nmap -sT -p10-100 localhost

For example scan all TCP ports (implicit 0-65535):

nmap -sT -p- localhost