If you imagine sticking a very thin straw into a fruit cake and then slowly pulling it out, the section of cake that is inside the straw is one core. They are looking for how many cherries there might be in the cake. In your husband's case they have stuck 6 straws into his left side and 9 into his right side. When they have looked at the section of cake inside the straws they found:
Left side - one straw had some cancer (cherry) but it was only 2% of the cake in the straw, the other 98% was clear (had no cherries at all)
Left side - the other 5 straws were clear
Right side - 6 of the straws had cancer in them and between 10% and 40% of the cake in each straw was cancerous (so they can see lots of bits of cherry but also lots of normal cake)
Right side - 3 straws were clear
Basically, they found a tiny amount of cancer on the left and rather more on the right but no cores were half cancer or worse.