A prentbriefkaart or ansichtkaart is a postcard. Postcards became popular in the early 1900s. Old postcards can give you a good idea of what the town looked like when your ancestors were living there.
It’s also worth asking family members if any of them have old postcards. Among the papers I inherited from my grandfather and grandmother were postcards they sent each other when they were engaged and he was serving in the military.
Digitized postcards can often be found on websites of archives or historical societies. This will only include older postcards because more recent ones will be protected by copyright. You can also try auction sites like EBay Delcampe, or Ansichtkaartenbeurs to buy originals.