AUDI A4 1998 Warning light problem? Help please!

I just arrived at work (without my manuals!) & had the top left of six lights flashing most of the way here - it looks like a dipstick type red icon going into some liquid, but I dont think its oil?

I topped up my water, which was low but this didnt solve the problem, hopefully it'll be something else but wold be good to know & rectify before I travel home!

Many thanks in advance