Help understanding numbers

Hi

im a newbie and just looking for a little help!

My father in law has colon cancer, also stomach, kidney cancer and lymphomas!

he was told today that on the scale of 1-100 he is now at 1 whilst previously he was at 30

We know this is good news but as my father in law is 71 and was quite emotional at the time he did not know what these numbers meant!

could anybody help with this please?

Thank you x