Welcome aboard on the forums and sorry for the delayed reply over Christmas 
Ableton Live will display a colored area ( it can be different than Red ) when thereās a Midi controller connected to your computer and controlling Live, so thatās just what this is. If you have multiple controllers interacting with Lives, you will see different colors.
Hope this helps !
Cheers
really great stuff awesome!
Welcome aboard on the forums !
Excellent tutorial! I use Logic Pro and have purchased Ableton Live. Absolutely thorough and well explained. Hope there is an Advanced version coming soon.
Welcome on the forums !
Thereās a Ableton Live 11 Level 2 course available here in case you havenāt checked this one yet :
Ableton Live 11 Tutorial for Beginners - Level 2
Youāll find all Ableton related courses here 
Now it starts to make senseā¦ Brilliant thank you !
Nice course for beginners. Loved it
Looks like a good course
Looking forward to getting stuck into this as a complete beginner, I hope this will have me up and running in no time.
Welcome aboard on the fourms !
Hope yuāll enjoy the course and thanks for your comment 
Great Course. Was really thorough and definitely helped point out some new functionalities. Also was helpful in sharing technique tips and workflow process ideas. Very helpful. Good Work P-Lask!
Welcome aboard on the forums and thanks for your comment !
Great course. Very well explained for anyone completely new to this.
Welcome aboard on the forums @adzyy and thanks for your comment !
Happy to hear that you enjoyed the course
Really like the look of this course.
Iāve been a pretty tepid and off and on producer since about 2019-2022. I got this course to brush up on my Ableton skills since I havenāt used it in years, and this is the first course that didnāt prattle on about compression without any explanation as to why itās needed and just focused on the fundamentals. I actually enjoyed mixing for the first timeā¦Like actually enjoyed itā¦ cause I knew what I was adjusting and why.
Iāll never forget āmixing is 90% getting your volume levels adjusted.ā
P-Lask please make more courses. I would buy any of your courses on here, especially ones on how to make certain types of genres start to finish.
10/10 sigma Chad, skibidi rizz producer.
This was a great intro! V greatful tysm.
Fantastic Course P-LASK!!!
Great course, glad I picked this one.
Great beginners course.