a, ante, bajo, cabe, con, contra, de, desde, durante, en, entre, hacia, hasta, mediante, para, por, según, sin, so, sobre, tras, versus y vía.
All of the bove are spanish prepositions. These words are auxiliaries to describe a number of situations that would make a sentece have the right meaning..
In your example, "Sabe a Ajo" Sabe (taste) is the adjective that describe the flavor and ajo (garlic) is the descriptive portion of it. the sentence is describing that a certain item has the have a peculiar or predominant flavor to that bulb.
The prepositions usually have a meaning by themselves, but they will help better describe what you are trying to say, same cases with the English language.
The meeting is between 2 and 3 o'clock. (La reunión es entre las 2 y 3 en punto)
That tomato is between ripe and rotten. (El tomate está entre maduro y podrido)
The remote is under the couch. (El control remoto esta bajo el sofá)
The bird flies to the sunset. (El ave vuela hacia el ocaso)
That store does't opperate during the day (Aquella tienda no opera durante el día)
And so forth.
Hope it helped.