what does ‘catch a song" mean ?

I mean to get the words in a song by lstening..

the reason is ,its a song .its not the original pronunciation.

i agree!i think the reason is that there are a lot of liaisons in singing ,much more
than talk

and there are many slangs and idioms in some songs,which may bring you some difficulties to listen it.

I think it's also hard to concentrate on catching the words,for the accompanying music.It often let me astray

你听得出周杰伦唱什么吗？

回去补语法

the recommendation for me? could you point the falts for me?thank you.I need to mend it.

rephrase your sentence like this:
(any) recommendations for me? could u point the (faults) out for me? i need to (fix it up).
this is going to be better

rewrite the title u've written down:
Why did I feel it's harder to catch the meaning of a song than understanding a part of a conversation?

继续改～～仍然觉得别扭
Why I felt it's harder to catch the meaning of songs than understanding conversations.

thank you.It's my pleasure to have my faults corrected.