Reading is understanding writing in a language. Fundamentally, reading is the way we look at certain marks and know what they mean.
Once it was possible to go through life without reading. After all writing goes back in human history only a few thousand years, and 200 years ago most men could not read or write. We know this is true because they could not write their own names on marriage records in churches. How did they live? Well, most men worked in farming, and you can do most of that job without being able to read. The wives could read: they lived at home before marriage and their mothers taught them. The boys went to work at, say, nine or ten, and never learnt to read.