The Spanish martillo (“hammer”) comes from the Latin malleus meaning the same. And from this Latin root malleus we get the English… malleable. So something that is malleable, changeable, is figuratively… hammerable.
We see that the Spanish m-rt-ll maps to the English m-ll.
Ganar (Spanish for “to win”) comes from the old Germanic root waidanjan, meaning “to hunt”. From the same root, via French, we get the English… gain.
The g-n pattern is clearly visible in both.
Interestingly, this is almost an example of the w- to g- pattern, like guerra and war. It has the original w- root in the original word but the modern words, in both Spanish and English, use the g- sound (since the English word came indirectly from Latin via French).
The Spanish tirar, meaning “to throw, to pull”, has two unexpected cousins: the English retire and tirade.
The two English words come from the same root, also meaning the same. Thus, retire literally means, to pull back (the Latin root re- means “back”): to go on a tirade is literally just throwing out lots and lots of words!
Oddly, no one knows where this whole family of words comes from. No obviously similar cognate exists in Latin.
The Initial F, followed by a vowel, disappears: So, “hoja“, meaning “leaf” (in all senses: the autumn trees, the piece of paper) is thus, from the same Latin root as “foliage“, the green plant leaves!
Cosecha (Spanish for “harvest”) comes from the Latin collectus, meaning, “collected.”
This makes sense: a harvest is, well, just collected.
Although the English collected is almost identical to the Latin, we can see how the Latin changed into the Spanish: the -ll- turned into an -s-, in a curious change. But — as is more common — the -ct- became a -ch- (think nocturnal/noche or octagon/ocho). Thus, the c-ll-ct of collect maps to the c-s-ch of cosecha.