A pangram is a sentence or block of text that contains all the letters of the alphabet. In English a pangram must be at least 26 letters long, although they must often be longer in order to make a grammatical sentence. In Spanish they are at least 29 letters long, assuming you include the two digraphs ll and ch (as the Spanish alphabet is wont to do). A full Hindi pangram would have a minimum of 58 characters. A Chinese pangram would have over 47,000 characters. There aren't very many Chinese pangrams.
Pangrams are most traditionally used in typography to demonstrate the appearance of text in context; these days they may be used to check the graphics display of screens. They are also used as typing exercises, although these days pangrams are more often viewed as a form of word game. The most famous pangram in English is "The quick brown fox jumps over the lazy dog", which has been around since at least 1908 when it appeared in Robert Baden-Powell's book Scouting for Boys, where it was used to practice signalling .
There are millions of other pangrams (literally!). Here are some of them:
'Pack my box with five dozen liquor jugs'.
'Waltz, nymph, for quick jigs vex Bud'.
'Jackdaws love my big sphinx of quartz'.
'Quick zephyrs blow, vexing daft Jim'.
And most impressive, "Mr. Jock, TV quiz Ph.D., bags few lynx", which
uses only 26 letters, as does 'Cwm, fjord bank glyphs vex't quiz'.
And here are some in other languages:
French:
'Whisky vert: jugez cinq fox d'aplomb'.
'Portez ce vieux bon whiskys au juge blond qui fume'.
'Voyez le brick géant que j'examine près du wharf'.
German:
'Zwei boxkämpfer jagen Eva quer durch Sylt'.
'Franz jagt im komplett verwahrlosten Taxi quer durch Bayern'.
Dutch:
'Zweedse ex-VIP, behoorlijk gek op quantumfysica'.
'Sexy qua lijf, doch bang voor het zwempak'.
'Pa's wijze lynx bezag vroom het fikse aquaduct'.
Latin:
'Gaza frequens Libycos duxit Karthagos tripumphos'.
Spanish:
'Jovencillo emponzoñado de whisky, qué mala figurota exhibes'. (Thanks to tres equis for this one).