These are male to male jumper wires used in connecting the male header pin of any development board to other development boards having a male connector.
They are simple wires that have connector pins at each end allowing them to be used to connect two points to each other. Jumper wires are typically used with breadboards and other prototyping tools in order to make it easy to change a circuit as needed.
40 strip Male to Male jumper wire each cable length about 20cm or 8-inch.
This has two ends where both male ends have a pin protruding and can plug into things. Male-to-male jumper wires are the most common and what you likely will use most often. When connecting two ports on a breadboard, a male-to-male wire is used.
It is used to interconnect the components of a breadboard or other prototype or test circuit internally or with other equipment or components without soldering.