Details

LegendLabel->None specifies that no label should be given.
LegendLabel->Placed[lbl,pos,fun] puts lbl with fun applied at the position specified by pos.
When the label position is Bottom, Top, Left, or Right, the label will be inside any structure created by LegendFunction.
When the label position is Below, Above, Before, or After, the label will be outside any structure created by LegendFunction.

Examples

Use no label:

Wolfram Language code: SwatchLegend[63, Range[4], LegendLabel -> None]

Use any Wolfram Language notation for labels:

Wolfram Language code: SwatchLegend[63, Range[4], LegendLabel -> Sum[f[i], {i, Subscript[i, max]}]]

Place the label below the legends:

Wolfram Language code: SwatchLegend[63, Range[4], LegendLabel -> Placed[BesselJ[1, x], Bottom]]

The label is inside the wrapper function specified by LegendFunction:

Wolfram Language code: SwatchLegend[63, Range[4], LegendLabel -> "label", LegendFunction -> "Frame"]

Place the label outside of LegendFunction:

Wolfram Language code: SwatchLegend[63, Range[4], LegendLabel -> Placed["label", Above], LegendFunction -> "Frame"]

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