Difficulty reading signs from a distance. What is that?

Nearsightedness. You need an eye exam, as you may be nearsighted, which means you have difficulty seeing things that are far away, such as signs on the road while you're driving. You may need glasses or contact lenses.
Many possibilities. This depends upon your age. If you are in the 10-40 year old age group, the most likely cause is uncorrected vision eyeglass needs. In the older age group there are some diseases that can cause this problem including glaucoma, cataracts and macular degeneration. Diabetes is a possibility at any age. See your ophthalmolgist to sort this out.