As you know, 'can' is a verb meaning 'be able to'. 'Can' is also a verb meaning, as you said, 'preserve by sealing'. 'Can' is also a noun, meaning 'tin used for preserving'. 'Canner' is a noun meaning 'someone who cans food'. The whole phrase means: 'Are you able to preserve a tin the way a person who cans food is able to preserve a tin?' I hope that helps, but if you still find the sentence confusing, don't worry. It's intended to be confusing.

Yes, you are on the right track. Instead of saying, "Preserve by sealing," though, I would add, "in a can or bottle."