Upvote:1
The unreadable scribble on your passport, however unlikely, is really a number, and most likely it's a "90". When you enter Colombia, you get questioned about your intentions, then you get a stamp, and on that stamp, two scribbles. One is to indicate which of the 9 possible entry reasons applies to you (5 means tourism), a the other scribble is the amount of days, which per default is a "90".
You can renew it once while in Colombia, for 90 more days, for a fee which should be around $30, IIRC. You need to visit a DIAN office and be prepared to spend a whole morning there.
You cannot renew it twice.
If you overstay, be prepared to pay a fine which will be no less than half a minimum salary. Think of $120. It's an administrative sanction, it does not leave legal traces if you want to travel to Colombia again, but renewing is cheaper.
You will not be allowed to enter Colombia if, during the running year, you have already spent 180 days in the country, 180 days being the maximum cumulative amount of days allowed for tourism during a solar year.