When you are searching in the Users tab, the three tags are the tags that you've earned the most votes in during this week (by default). It follows along with the number above it, which is the amount of reputation you've earned this week. They're basically identifiers to what you're currently active in.
For example, mine says php, arrays, and bugs because of this answer I made which gave my 80 votes in each of those tags.
Edit from comment: I believe this can occur because the information shown in the Users tab, determining your active tabs, is live (as you currently stand), while the information on your user page which displays number of votes for each tag is cached. Not 100% sure, but the Users tab appears to be counting your recent activity in those tags already when your tags list hasn't updated yet. Or it could (possibly) be a bug.
You have earned 268 reputation already today, so I'd expect your tag values to change a bit when they recache.