The verb "gusti" means to have a taste, not to taste something. It is an intransitive verb so takes no object, we attatch adverbs to it not adjectives. "La kuko gustas dolĉe" : "The cake has a sweet taste"
The indefinite relation suffix -um- is used to create "gustumi" with the meaning of to taste something. Gustumi has an object as one is tasting something.
Also the suffix -ig- to cause, can be added to gusti to create "gustigi" meaning to taste like or to cause a taste of.
I just learnt recently that words like "decimal", "binary", "octal" etc use -um- ; For example dekses+um : deksesuma = hexidecimal (16), du+um : duuma = binary, and so on. But yes it's used with and to create several verbs, nouns, and adjectives.
This one "brakumi" = to hug; is a very common use. An indefinite relation to do with arms (brakoj). Others are:
- palpebro (eyelid) → palpebrumi = to blink
- aero (air) → aerumi = to air out
- komuna (common) → komunumo = community
- sukero (sugar) → sukerumi = to cover with sugar
- pendi (to hang) → pendumi = to hang oneself je la kolo por mortigi...
- folio (sheet/page) → foliumi = to flick/leaf through a book
- dekstra (right side/handed) → dekstruma = clockwise
"Mangxo" is the generic/abstract "food". "Mangxajxo" is the specific/concrete "meal".
That is nearly but not totally correct ... Manĝo manĝo can mean: „food“, „the action of eating“ (= manĝo/manĝado … the latter if the action is during) and also „meal“ vespermanĝo = dinner Manĝaĵo manĝaĵo only means „food“ i.e. anything that can be eaten … (synonym „nutraĵo“) of course also „meal“, but not the action of eating vespermanĝaĵo would not mean dinner but only „food for dinner …“ of course „vespermanĝaĵo“ would be a very strange word and not normally used, but the construct would be possible.
The third meaning "to try al Little Piece of to see if I like it" is "mi provas" .... this is something completely different from "gusti" and "gustumi" ... It's a big problem of the English language that the same word has often very different meanings ... (exactly this makes English in reality very difficult and a very bad joice as the international language ...) --> One of the principles of Esperanto is "1 word = 1 meaning". Of course this is an impossible goal to be reached 100%, but almost a word in Esperanto has a much more precise meaning in the case of gusti/gustumi/provi you can clearly see this. A problem for English native speaker may be that they are often not aware about the different meanings of one specific word in English. Here the learning of a precise language like Esperanto can help to get this understanding of the own language. (Sorry for mistakes, English is not my native language ...)
ajx marks a thing as a concrete object, the <noun> that is <verb>ed. It can also be thought of the concrete thing that is made from the general concept.