Simplify the following text for a Grade 12 native English-speaking person.
Original: In electronics , a multiplexer or mux ( occasionally the term mul-dex is also found , for a combination multiplexer-demultiplexer ) is a device that selects one of many analog or digital input signals and outputs it into a single output line .
Simplified: In electronics , a multiplexer or mux is a device that selects one of several analog or digital input signals and forwards the selected input into a single line .