Yes, maybe so, but "multiple" doesn't give any better idea of more than just a couple than many, so maybe "a few" is better than multiple ?
Wikipedia tells me that an overall in English is snickarbyxor in Swedish, whereas en overall in Swedish is a jumpsuit in English. I've got to admit I never use the word overall in English so I'm not totally sure what it stands for. Where are you from and what do you use the word for?
They seem to be thinking of en arbetsrock or skyddsrock, these can be an overall in English. But the word we're trying to teach is the normal simple word en rock which is 'an overcoat' or 'coat' in English. If you image google trench coat you'll see some typical examples:
(link to such a search: http://bit.ly/1NT1li1)
"Several" is countable though not a specific amount, not so many that you cannot count them, but more than two and not that many. The items are viewed as individual and separate. http://www.merriam-webster.com/dictionary/several (Often used for three or four, but can be a bit more.)
Some is a completely undetermined amount - a little or a lot - we just don't know. The items are viewed as a whole group, indistinct from each other. It is more than none and less than all. It can also be used with uncountable things, such as water. http://www.merriam-webster.com/dictionary/some