Can I connect external speakers to Mac mini m1

Yes, I assume you mean some professional or prosumer speakers (if not please specify) that use ¼" TS audio jacks. You need a 3.5mm stereo to single or dual ¼" speaker cable to do so. Like this: https://www.amazon.com/gp/product/B00ZKM3SDO/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You also need an amplifier or use powered speakers since the Mini audio

output power is only sufficient to drive headphones.

Yes, there is a 3.5mm aux port below the 2 USB-A or if it runs USB-A/USB-C plug it into the corresponding port