if so, there are NO sounds included at all.
It is MIDI. MIDI is event data that instructs a software (virtual) instrument or hardware instrument what to play, how, when and for how long.
As noted on its product description page,
this MIDI pack includes MIDI containing parts that are complementary to 2 separate virtual instruments.
The MIDI designated for the string parts could be played by a virtual instrument
like the Mellotoon or String Machine Toontrack sound libraries
while the MIDI designated for the keyboard parts could be played by a virtual instrument like any Toontrack sound library.