It means that different people (folks) do different things (strokes) to get the same outcome. It means not everyone is the same, or has the same beliefs or methods.

It just means different things suit different people. Each to their own. What Robbie Williams has tattooed across his clavicles. No-one seems to really know what the "strokes" refer to. Affectionate gestures? Moving through water (ie. rowing/swimming)? Painting? The phrase seems less than a hundred years old, so if it has to do with whipping slaves, then the people who came up with the phrase certainly weren't being whipped. I can't say that strokes definitely refers to drum beats, but there is a quote from Thoreau which gives the same sentiment: "If a man does not keep pace with his companions, perhaps it is because he hears a different drummer. Let him step to the music which he hears, however measured or far away." Interestingly, the theme song for the American sitcom "Diff'rent Strokes" makes reference to both expressions in the lyrics of the theme song.

Different strokes for different folks is a proverb that seems to have originated in the US before the civil rights movement began, and was used to say that we all like different things, but that's OK. It is thought that "strokes" might refer to the whipping that black slaves received and a reference to white slave owners whipping their slaves differently. This is an example of "dark humour" where people joke about their punishment as a coping mechanism.