Timber frame is like building with big wooden puzzle pieces. There are long pieces of wood called beams that go along the top and bottom of the building, and shorter pieces called posts that go up and down to hold it all together.
The beams and posts fit together really well, almost like a lego set. People have been using timber frames to build houses and buildings for thousands of years because they are strong and can last a really long time.
Nowadays, people still use timber frames to build houses, but they use machines to cut the wood into exactly the right shape and size. It's kind of like when you use a puzzle cutter to make a puzzle piece fit perfectly into its spot.
So, timber frame is building with big wooden puzzle pieces that fit together really well and make a strong building.