What is SMOKE -FREE?

My mom was so happy that I can finally able to read some words now. My new school was a good reading trainer. Some of the words I knew were everywhere so I can easily get to know and familiarize with them. Some words I know were number words such as one, two three and so on and so forth. I also know some words such as the, she, he, they, we, love, me, is, are, daddy, mommy and so many more and most of them were in the books that mommy is reading me.  I also started to read words that posted in billboards, in streets, in ads and in TV. One time I saw the words "SMOKE-FREE" and I ask mom what's that mean. I thought that means that you can smoke anytime you want but it's not. Smoke free means, the area is FREE of SMOKE and in short, smoking is not allowed. But one time I saw a man smoking but mom said it was an electric one so it's safe.