Let's look at the sentence: "Mangrove trees put the extra salt into their leaves so it can be shed later."
Overall, the sentence is good! It talks about how mangrove trees move salt into their leaves to get rid of it later.
One small fix: the word "shed" here is fine, but you can also say "dropped" or "fall off" to make it clearer for you.
So, you can say: "Mangrove trees put the extra salt into their leaves so the salt can fall off later." Or keep it as: "Mangrove trees put the extra salt into their leaves so it can be shed later." Both are correct.
Great job!