I feel like thinking of "mal" as "once" or "a single time" is helpful for me in understanding its meaning in this example. I takes my brain from something specific and intentional where it's used with a specific number, e.g. "drei mal / three times" to something more casual "mal / a time". As in, "yeah, I guess that's worth a single look at what's inside". It works for me in the other ways I've heard "mal" explained as a softener, or lending a bit more politeness to a command, because it feels like it's more an optional activity than an must-do. I don't actually know if that's correct, it's more just a mnemonic device than anything else.
Again, I think 'mal' means 'time' only in the sense of an occurance, as in "you can go down the slide 2 more times", NOT in the sense of 'then it's time to go home'. That would be Zeit. Just because we use the word 'time' to mean several different concepts in English, doesn't mean every other language does the same.
"Lass uns sehen, was da drin ist." is okay. I would prefere a "!" at the end.
"Lassen wir sehen, " does not work, "lassen" does not has the form of an order like "Let us see!" and you need "uns" instead of "wir".
((A sentence with "lassen wir sehen" could be: "Lassen wir die Kinder den Computer sehen?" ~ Do we offer the children the possibility to see the computer?))
"Mal sehen." (=Lass uns mal sehen) is not an order but it covers the meaning of "Let us see" very well.
Mal has another meaning distinct from time. It can be used as a modal particle to imply a more polite or softer tone to a sentence. Used this way, it has no direct translation into English, because English has no modal particles.
An easier to understand example of how mal can be used this way is, "Du musst mal deine Mutter anrufen." Here "mal" conveys the difference between telling someone to call their mother and urging them to call their mother.
"English has no modal particles". This may well be true, but English does use similar techniques to soften questions and orders. "Right, let's see what's in there, shall we?" "Well, what's in there, then? Should we take a look, do you think? Who's game?" Words like "right", "well" and "oh" serve as ameliorating particles in English, alongside turning orders into "inclusive" questions using we instead of you, and a liberal sprinkling of the conditional mood.
"Mal" sounds like the apparently meaningless, words that crop up in English as "softeners" in conversation. I'm sure there must be a technical term for them, but I don't know it. They are distinct from slang, however. I am thinking about words like well and oh, which appear at the beginning of questions or orders to make them more palatable. "Oh, Seán, would you mind picking up my dry cleaning while you're in town?" "Well, I'm not sure I can today. Is it urgent?"
Translates as "Seán pick up the damn cleaning already!" "Do it yourself, ❤❤❤❤❤❤❤. Am I your slave?"
I'd like to know more about this comma. Why is it here? With most dependent clauses that I read, there is no comma but the verb comes before the subject instead. I'm sure that this isn't the same kind of sentence. I've seen this kind before, and it irks me that I don't understand why the comma is there.
No -- and "surely" is a big leap from "may (in some contexts) be translated".
This is not the noun Mal but the particle mal, which is only capitalised in this sentence because it's the first word.
And even the noun Mal does not mean "time" in the sense of "the right time" or "high time", but only in the sense "instance, occurrence" (e.g. "next time he will not be late" or "I will tell you this ten times").
I think that the meaning behind the word 'mal' in this phrase is loosely coming from the concepts of arranging/planning/scheduling something to be done or to happen. Those concepts (all verbs) could be expressed using the word 'time'; for example "Departure from the station is timed for tomorrow morning"- although this seems to me to be something that would not be heard in my area of the US. The phrase 'mal sehen' (we'll see) gives me the feeling that the speaker is thinking about the request, and may make arrangements to fill/deny it. In the lesson sentence, 'Mal sehen, was da drin ist', the phrase gives me the feeling that the speaker is saying 'Let us arrange to see what is there.'
As a side note, 'mal' is also used to express the multiplication process of two numbers: "Seven times five is thirty five" = "Sieben mal fünf ist fünfunddreißig." Here, 'times' has nothing to do with the time! ;-)