Translation:My grandmother is no longer able to ride a bicycle.
The word order in Czech is very flexible. When we put the verb at the end, we stress it (provided we keep the normal intonation when pronouncing the sentence).
Basically, the new information here is that she can't do it any more. Bike riding was probably mentioned in some preceding sentence.
Your sentence "Babička už nemůže jezdit na kole" is the basic form of the sentence and does not assume any preceding context.