父is the humble word for father, used when referring to your own father to people outside your family. When addressing your father directly or speaking about someone else's father, the honorific お父さん is used.
That is how Fuguro works. It brings 父 back for review right before you forget it, each time a little later, until it sticks for good. You hear it spoken aloud, and you meet it again in stories you can already read. The first five levels are free.