Math skills are important for understanding our world, and you can teach them very early on in a child's life. You can even do it here at the library!
Count: learning the numbers is of course a foundation to mathematics. Count what you see around you. Count what see you in books, count people, count blocks, and do it together and out loud! You'll get some bonus vocabulary skill-building and probably have a lot of fun, too.
Sort: understanding patterns helps us learn how to predict outcomes and build logic skills. Sorting is also a good way to build hand-eye coordination skills.
Measurement: talk about different sizes of the books, chairs, benches, and people around you. This builds spatial awareness as well, which later translates into geometry!
Here are some more resources: