The light sensor on the Circuit Playground Express is in the lower right corner below push button B marked with an ear.
This microphone is a bit different than some used in Arduino projects. Instead of an analog microphone, which requires an external op-amp and level management, the Circuit Playground Express uses a PDM microphone. This is a digital mic which is a lot smaller and less expensive. You will need to use MakeCode/CircuitPython/Arduino support libraries to read the audio, you cannot read it like an analog voltage.
The following pages show how to easily use the microphone in your own project.