Translation:Your vacations are more expensive than my house at the lake.
'By the lake' was marked wrong. This is just as good English as 'at the lake'. 'By' implies 'besides' better than 'at'.
Der See means "the lake". Die See means "the sea, the ocean". It is less commonly used. German uses more often das Meer or der Ozean for the latter. Check out Bodensee and Nordsee on Google Maps and see if you can figure out which one is feminine and which one is masculine :)
depending which English you're talking about. American English doesn't use holidays. We say we're going on vacation. Holiday is a specific day. Like Christmas is a holiday. In the US, you don't go on a holiday. You might be on vacation during the holidays (in general, if someone says 'the holidays' they're probably referring to the period of time between Christmas and New Years).