Translation:He kicked a stone and now his foot hurts.
This is a really good question that's had us contributors stumped for a while. But I'll try to answer now that we've had the chance to discuss it among ourselves.
Sparka and sparka på is not the case of a regular verb and a phrasal verb, because the particle på isn't stressed. So that's ruled out.
Rather, the inclusion of "på" here triggers a sense of referring to a non-delimited process, as if kicking a stone wasn't just a single general action. This is not the same as the English continuous aspect (to be + verb + ing), but it isn't far from it either if used as a comparison.
The same thing can happen to other verbs as well. For example, jag skriver på en bok includes this sense of a process that isn't delimited rather that just referring to writing a book in general.
But in the sentence above, "han sparkade på en sten..." it sounds non-idiomatic to not include på. I'm not sure as to exactly why, as we're dealing with tiny nuances that I'm just too much just a native speaker to explain properly.
I hope this reply can be of use to you, despite the limits of it. :)
In that example, the på serves basically the same purpose as the "on" in e.g. "I'm working on a book". But you can still very well say jag skriver en bok to mean "I'm writing a book", and you can say jag skriver på en bok for "I'm writing a book" as well.
"I write on the book" would be jag skriver på boken.
Pretty sure this one is due to the DL software creating contractions where it should not. The sentence would have been "...and now he has pain in the foot" before the software mangled it. And whilst that isn't the most idiomatic way to phrase it, it certainly is not incorrect.
rock is an accepted answer. Although 'rock' and 'stone' clearly aren't ""absolutely, 100% synonymous", it isnt' all that easy to pin down the difference. I found a fun blog post about it here: http://geologywriter.com/blog/stories-in-stone-blog/rock-or-stone-is-there-a-difference/
Thank you for adding rock in as an accepted term! Perhaps I should have been more clear with my statement though: rock and stone within the context of the sentence ("something he kicked, which led to his becoming pained") are 100% synonymous.
Something to be aware of however: if you search Princeton University's WordNet database, which arranges items by synonym sets, the two words are so closely tied in the form of their first two definitions that they are listed together instead of as hypernym, hyponym, or even meronym:
S: (n) rock, stone (a lump or mass of hard consolidated mineral matter) "he threw a rock at me" S: (n) rock, stone (material consisting of the aggregate of minerals like those making up the Earth's crust) "that mountain is solid rock"; "stone is abundant in New England and there are many quarries"
I did a cursory check to try and find comparable words to "rock" and "stone" in Swedish, but was unable to discover anything except for "sten" - are there any other common words that you could see being plausible?
Thanks for your help and understanding!
I didn't add it, it was already accepted (it was something else that wasn't accepted). But I totally agree both work just as well in this case. There's a word klippa in Swedish which is a bit like 'rock', only more – the difference between 'klippa' and 'sten' is much bigger than between 'rock' and 'stone', klippa is only a big rock that is like a part of a mountain or so, never something you could throw at someone. The word is probably a cognate with cliff in English and there's a big overlap, but Wikipedia for instance lists klint as the counterpart to cliff.
And 'rock' in the geology meaning you mentioned ('material consisting of an aggregate of minerals') is en bergart in Swedish.
It's a hard subject :D