Asking the time is one of the easiest things that can be done without words: it's only necessary to raise the left arm a little bit, point at one's wrist with the right forefinger, and give a I-am-at-a-loss face. The answer could easily be performed with the same means: just by showing the watch or even signalling the sun (this only works for the most experienced ones), the whole interaction of asking and giving the time can be completed.However, the time is usually given using words and it's then when we have to be competent enough both to understand others and to make others understand us. Everyone knows that when studying a language the time is an easy-to-learn recurrent topic, but there are occasions in which we may get confused. In English we say “It's half past two” for 2:30 when we are asked “What time is it?.” We can see that there is concordance between the question and the answer, i.e. we use the pronoun “it” and the verb “is” in both of the instances. So far so good. But what happens in other languages? In Spanish sometimes there isn't this kind of concordance. For instance, for the question “¿Qué hora es?” (“es” being singular) we may answer “Son las dos y media” for 2.30 (note that the written format is different from that of English). Then “es” and “son” are singular and plural respectively. This is beacause the concordance is done only within each sentence.
In Portuguese, French and other languages of latin origin the same happens. We say “Que horas são?” (but we don´t say “Que hora é?”) and “Quel huere est-il?” when we want to know the time. The answers follow more or less the same pattern as in Spanish, but in French it's mandatory to use the word “heures” in the answer but it's almost inadvisable to use “minutes” when referring to the minutes. For instance, right now “il est 8 heures 15” and that's it.
Although giving the time may seem a simple task, it gets complicated when we are at a hurry and someone asks us the time in the middle of the street... in a few times I've even given the wrong time in my own language! Well, perhaps it's safer to point at the sun and let the other person guess the time of the day.
Note: Beware those who travel to Catalunya since there time is handled a little bit different from the rest of the world. For our surprise Catalans say, for instance, “Es un quart de dues” when it´s 1:15 (i.e. a quarter past one) or “Son tres quarts de set” when it's 6:45 (i.e. a quarter to seven). It´s quite complicated to understand it and even more to learn it, so you should stick to the whole wrist-pointing thing if you want to know the time 
