In Italian, "bicchiere" means both "glass" and "goblet" https://translate.google.fr/?hl=fr#it/en/bicchiere
From what i have found it appears that Taza, and Bicchiere are forms of cup, and Vetro or Cristallo are forms of glass, i guess a technicality. I could be wrong.
"il" is masculine. "la" is feminine. "l'" is used for both when the following noun begins with a vowel. for example, you say "la mela" (the apple) and "il pesce" (the fish), but you can't say "la armatura" (the armour) or "il esempio" (the example): you have to say "l'armatura" and "l'esempio".
Sometimes the gender of a noun can be determined by looking at the ending of the noun. At other times you just have to memorize the gender.
"Il" is used with most masc. nouns.
"La" is used with most fem. nouns.
"Lo" is used with masc. nouns that start with gn, s+consonamt, p+consonant, x, y or z.
"L'" is used with words that start with vowels.
"I" is the plural of il.
"Le" is the plural of la.
"Gli" is the plural of lo and l'.
Il ragazzo → i ragazzi
La ragazza → le ragazze
Lo studente → gli studenti
L'uomo → gli uomini
It looks complicated, but that's just because of lo. You get used to it quickly.
"El" is not an Italian word to my knowledge.
Both masculine singular and feminine singular nouns can end in "e", as well as feminine plural nouns. Since the exercise was to translate "The glass" into Italian, and "glass" is singular, and happens to be a masculine noun in Italian, you would not use the feminine plural definite article "le".