There's an unmarked tiny pill shaped port on my 13 inch mid 2010 MacBook and I don't know what it is.

Looks like a normal Thunderbolt 3 or 4/USB-C port to me, but from then scale it looks somewhat smaller

Have you tried to use it?

USB-C cables look like this:

Your specs show this so I'm not really sure:

Connections and expansion

• MagSafe power port
• Gigabit Ethernet port
• Mini DisplayPort
• Two USB 2.0 ports (up to 480 Mbps)
• Audio in/out
• Kensington lock slot

Does look like a lock slot, but again, scale makes it unclear.

Lock slot is the "pill" shaped "port" the article said.

A picture would be nice. All Thunderbolt/USB-C ports are sort of "pill" shaped.