I want to share a playlist but some tracks have red broken rectangles. What does this mean?

[redke]

I've made a playlist of about 15 tracks found on Spotify, that I want to share with a friend.

Three of the tracks have little red broken rectangle symbols next to them.

Nine of the tracks have grey rectangles with music notes in. I notice I have these tracks myself in my iTunes library, but I didn't bring them to the playlist from there. I found the tracks on Spotify.

What does these symbols mean? Can I still share these tracks with my friend?

Thank you for your help!