What you share could be anything such as some songs you sang, something you learned about singing, your singing experience, or some all time favorites. 
As for me and the inspiration for this post:
I got to chat a bit with a new member here about singing which, perhaps less so now, I've a hate love relationship with.
The thing is, I used to find that some songs were easier for me to sing naturally than others, as someone with little to no a knowledge of singing, and no training.
Though until now I couldn't quite figure out or put words to why that was. However, my making the effort to find out why to answer his question helped to give me more clarity. I think I previously thought it was a me issue when I struggled with some songs. Which is likely where the hate part primarily came from. Rather than understanding that it is more to do with different factors, such as the vocal demands of a song, and that just because I love a particular song doesn't necessarily mean I can sing it as well as the others. So with this greater understanding I can now look for songs that are a better fit for me, rather than singing random songs. Or because it's a song I love, if I'm looking for better results.
For context, this was a response I gave him about it:
I'm not sure the terminology for it or that which most applies to me exactly. Though I think that I've a soft or low vocal range and that I can sing more slow paced songs or ones that have a variety of vocal ranges. So here are a few song examples I can sing at least decently, whereas some no can do:
Homesick by Kane Brown, One Dance by Drake, Apologize by Timbaland, Disturbia, and Under my Umbrella by Rihanna. While a song like Home by Daughtry, which is one of the ones I love, I don't think I sing as well as the others. Which is probably because it has a sustained vocal range that doesn't come naturally to me. Thanks, your question gave me more clarity on my singing ability, and repertoire.