This sounds a bit like the spoof film "Saturday the 14th" from 1981. I remember them opening up and reading a book and a bunch of monsters come out from it. It was supposed to be a horror-comedy. But, depending on how young you were, I could see it being more on the horror side for you.
"Primarily a spoof of the Friday the 13th series, but also takes shots
at several other horror films. After his family moves to a new house,
a young boy discovers a mysterious book describing the curse hanging
over the date of Saturday the 14th. Opening the book releases a band
of monsters into the house, and the family must join together to save
themselves and their neighborhood. "
Wikipedia has a similar description:
"Billy finds the mysterious book. He reads of a curse hanging over the
date of Saturday the 14th. As he turns the page, a monster is
unleashed, and with each turn another disappears from the page and is
materialized within or outside the home. The house is soon swarming