No, ‘can’ is not a preposition. It is actually a modal verb used to indicate ability or possibility. In English grammar, prepositions are words that show the relationship between a noun or pronoun and other words in a sentence, such as ‘in’, ‘on’, ‘at’, ‘by’, etc.
For example, in the sentence ‘I can swim,’ the word ‘can’ expresses the ability to swim, while ‘in’ would be used in a different context, such as ‘I swim in the pool.’ Here, ‘in’ is the preposition that connects the verb ‘swim’ with the noun ‘pool.’