With Home Reach, you buy a share of your chosen home and pay a low monthly rent on the part you don't buy. You get to choose whether you buy a bigger share of a lower priced home or a smaller share of a more expensive one.
With the Taylor Wimpey partnership you can initially purchase between 50% and 75% of your chosen home and heylo will become your landlord, granting you a 125-year lease. This means you will be able to live in your home as if you've bought it outright. You can buy more of your home in the future and stop paying rent on that part.
You can find more details on the heylo Home Reach scheme here.