The short answer
Easements and rights of way grant others legal rights over part of a property, such as access or shared services, which can affect privacy and development plans.
A neighbour's legal right to cross your driveway, or a shared drain running under your garden, doesn't stop you buying the property, but it can materially change how you use it. These rights aren't always obvious from a viewing or a set of photos.
Why this matters for your purchase
Easements and rights of way are exactly the kind of thing the title review section of a PropM8 report is built to catch early, before it becomes a conveyancing surprise.