That means it has passed the Bobby test for accessibility. An accessible web site is one that can be accessed by anyone, whatever their age or abilities. Currently, many businesses are neglecting a large sector of potential customers of their online services - people with disabilities.
Disability increases rapidly with age and it is well known that the world's population is ageing.
Few organisations can afford to deliberately miss this market sector. Basically, designing to include disabled and older users means more customers. If web sites are not accessible to disabled users, this is not only morally unacceptable, it may in some cases also be unlawful. Companies who have web sites need to recognise the needs of disabled customers. Failing to do so, in the UK, conflicts with Disability Discrimination Act.