What is level access testing?

Short answer: probably here: https://www.levelaccess.com/accessibility-testing-tool-requirements/ I don't know of a single specific product or service known as "Level Access Testing." Level Access provides consulting and training around accessibility. Several of their offerings involve "testing" a web site or app for accessibility. These include automated testing (where computers look for common stumbling blocks) and manual testing (where human users who have a disability attempt to complete tasks and identify issues). The link above gives more detail.