How do I connect with a cable BOSE Sound Dock to my MacBook Pro

Are you talking about this? ("Bose Sounddock Series II Digital Music System for iPod")

https://www.amazon.com/Bose-Sounddock-Digital-Music-System/dp/B005LWY68E

That "30 pin male socket" on the front is for an iPod or iPhone with the old 30-pin dock connector that preceded Lightning (and USB-C, on some iPads). There may be adapters that let you connect to that dock connector, such as these $20 and $35 ZIOCOM Bluetooth receiver modules.

https://www.amazon.com/s?k=30+pin+ipod+adapter

https://www.amazon.com/ZIOCOM-Bluetooth-SoundDock-Connector-Lightweight/dp/B082D9YK8W/

https://www.amazon.com/ZIOCOM-Bluetooth-Receiver-Compatible-SoundDock-dp-B095NTMG8W/dp/B095NTMG8W/

The audio in port on the back of your Bose Sound Dock appears to be for a standard 3.5mm stereo audio plug. You'd just run a standard 3.5mm to 3.5mm stereo audio cable from your Mac's headphone jack to it. Probably you would want to start off with the Mac's output volume set low, then gradually increase it – to avoid blasting your ears and/or the speakers with too high of an amplification level.

You used to be able to find 3.5mm stereo cables at Radio Shack (R.I.P.), but I think that even retail outlets such as Best Buy, Target, and Walmart carry them.

Does its accompanying literature state you can connect with a cable? Does it have ports for that purpose?

The cable you need depends on what ports the two devices have, so you need to ID the year and model of your MacBook (Pro or Air) to determine what ports it has. And you need to ID the ports on the BOSE unit.

Pictures will be helpful if your can't ID the ports yourself.

Wed search finds: https://www.wikihow.com/Connect-External-Speakers-to-a-Macbook-Pro