The letters shown for the Values You Support indicate how well your portfolio as a whole is doing for that specific value. If you see an "A" next to Ocean Life, you know that overall, this value is respected by most companies in your portfolio that provide impact data.
The letters displayed next to Practices to Flag indicate how many companies in your portfolio are involved in this practice. If you see "3" next to Animal Testing, you know that three of the companies in which you currently invest practice animal testing. Companies that engage in practices you find unacceptable are tagged with a yellow flag icon.