I have a 1 year old baby she got prescribed 250 mg of amoxacillin 3 * a day and on the bottle it says usual dosage adults 250mg 3* day child 20mg 3*?

Depends on weight. Most antibiotics in children are prescribed based on the weight of the child and the infection being treated. Amoxicillin has a wide range of dosage parameters depending again on the infection. If you have any doubts call the doctor that prescribed the meds.
Kid not small adults. The dose of kids medicines varies by both weight and the problem being treated.For ear infections the range for amoxil (amoxicillin) goes up to 90mg/kg/day which for the average 1yo would be 900mg. For a UTI it would be ~ 25 mg/kg/d. Your doc appears to be treating your kid well. It is confusing when you see information that offers such different recommendations.
250 is correct. The usual Amoxicillin dose for a 22 to 24 pound child is 250 mg 3 times a day. That dose is based on weight. Usually that dose would be for treating otitis media (ear infection).