The phrase "few blanks" means that there are only a small number of missing or unknown pieces of information or details.
Sentences with «few blanks»
I started out by cutting out the book pages and trimming around the text so there were fewer blank spaces. (elizabethjoandesigns.com)
It is large but akward shaped and very few blank walls (one houses the door to the garage, another to the sunroom, another to the kitchen, and a bay window on the fourth). (theinspiredroom.net)
The Democrat prevailed 69 - 15 (there were a few blanks and write - ins.) (hudsonvalleyone.com)