A can is a metal container. A jar is made of glass. :) We know when we mean can (a container) and can (ability) because one functions as a noun and one functions as a helping verb. You can see this by the word order in the sentence, or the presence of other words... for example, "can" (ability) always has another verb that follows it. Look at the sentence, not just the word, and the difference is very clear.

A can is a round metal container you usually use a tool called a "can opener" for. (Or nowadays it could have a tab you pull). A jar is usually glass and you open it by screwing off a "lid". The word "can" is also used as the ability to be able to do something. As in "can we go now?" or "You can go to Europe to see your cousins." Nicoletta

"Can" is one of the most commonly used modal verbs in English. It can be used to express ability or opportunity, to request or offer permission, and to show possibility or impossibility. Examples: I can speak English Can I have a cup of coffe, please?

Thank you guys it was so helpfull

US English: Anyone can can food in a jar, but typically only companies can can food in a can. British English: Anyone can preserve food in a jar, but typically only companies can can food in a can. ;D