What a 0/5 rating means
On the comedogenic scale, a 0 means it will not clog pores for essentially anyone, including very acne-prone skin. That places Aloe Vera in the range most people, including many with acne-prone skin, tolerate well.
One thing the number cannot tell you is concentration. Ingredients are listed in descending order, so Aloe Vera near the end of a label is present in tiny amounts and matters far less than the same ingredient near the top.
About Aloe Vera
It is a botanical extract included for soothing or marketing appeal. A calming plant extract rated 0/5, well tolerated by most skin types.
On a label it can read as Aloe Vera, Aloe Barbadensis Leaf Juice, Aloe Barbadensis — worth knowing when you scan an ingredient deck.
Aloe Vera in makeup and skincare
It appears in 'natural' complexion products and soothing skincare. Its irritancy is rated separately at 0/5, which is low.