Penlon Cottage is in Llanaelhaearn, which is a small village on the way to the tip of the Llŷn peninsula. It's a detached cottage.
It sleeps six people in three bedrooms. There's one bathroom with a shower over the bath, and a separate downstairs toilet. It has a 4 Star rating. It's comfortable and modern.
You're about a ten minute drive from Trefor, and Trefor beach. The coast path is right there. The cottage has a patio garden and parking right next to it.
The facilities are what you'd need: washing machine, TV, included bedding and towels. A cot and highchair are there if you need them.
For a day out, you're well placed. Caernarfon Castle is about twenty minutes away by car. The whole of Snowdonia is on your doorstep for walking. The National Trust looks after a lot of it. Portmeirion is roughly half an hour's drive.
If you're planning around the area, Visit Wales has good information for the Llŷn.