wüstling - if you're going to think seriously about language translation in the future, then I must correct a misconception:
> Wie verwendet man dieses Wort im Englischen?
It's a mistake to think that a particular word in German has a table-lookup translation in English that can simply be plugged in to an English sentence. The same is true, of course, for every language pair.
Naturally, some words are so narrow in usage, and so obvious in meaning, that you could pretty much look them up in a table, and translate them that way. Like, say, "twenty-three", for example. Oh, but wait a minute--there's the phrase "twenty-three skidoo" in English so I guess you *can't* translate that with "drei und zwanzig." Oh, well.
You get my point, I'm sure. If it were that easy, computer programs with huge dictionaries would have long replaced translators. That this is not the case, even with the holy grail of machine translation occupying thousands of computer scientists and linguistis for over 40 years, should be sufficient to prove the point.
So what I'm saying here is, your question is phrased wrong. It's not, "How do you say 'mal' in English?" but rather, "How do you translate this German sentence into an English sentence that conveys the same meaning, as nearly as possible?"
In many examples of German sentences containing "mal", you may find translators using lots of different English words to convey the sense of it.
'Mal', in fact, is one of a small set of particles in German that are notorious for being translated with a large number of variations in English, depending on the original context. Other examples are aber, auch, denn, doch, halt, nur, schon and ja.
You could try an interesting experiment by coming up with ten or so sentences in German with 'mal' in them, and giving them to ten (or a 100) different translators, and see how many of them translate 'mal' into the same English word. I bet the percentage would not be high.