NO! Lightroom’s backup just backs up the catalog, and it doesn’t contain your photos – only references to where to find them and the data about them. You need to back your photos up separately.
Every time I hear someone say ‘I deleted the photos because I thought Lightroom backed them up’, my heart sinks.
I can’t say this loudly enough – back up your photos as well as letting Lightroom back up its catalog. Lightroom doesn’t do that for you.