A variable product is a product that has more than one option in attributes, for example, color, size, material. Instruction on how to create an attribute is here as soon as the necessary attributes are available, a variable product can be created, instructions on how to create a variable product is here
By default, variable product attributes are presented as a dropdown in WooCommerce. WoodMart theme suggests the option to present the attributes as swatches. Swatches are available in text, color, or image format. Swatches can be configured for global attributes only.
Swatches in the text format:
Swatches are enabled in Dashboard -> Products -> Attributes -> chose the attribute -> Configure Items -> Edit -> Enable swatch