If your child is used to doing a worksheet or two, they will be able to do this quite easily, and will understand that they need to complete the task before they can move on to the next activity. Worksheets also help your child to learn how to follow instructions, and teach them about following rules.
A comprehensive set of worksheets covering a variety of subjects can be used to expand your child's learning experience. A worksheet about shapes can be used as part of a game to find shapes around the house, counting worksheets can be used to count things you see in the grocery store and so on.
By the time your child is ready for kindergarten or school, they should be able to recognize their own name and other simple written words. The sounds of each letter of the alphabet should be familiar to your child, and they should understand the principle of reading from left to right, which way to hold a book, and possibly even be starting to read three and four-letter words.
The first step to teaching the above is strengthening the small muscles in the hands and wrists that are used in handwriting. This process is often referred to as building fine motor skills. You can encourage fine motor development by having your child use art supplies like crayons, paints, markers, glue and scissors.