The easiest way is to check if your jack has the combo jack symbol (headphones with a mic aka headset) next to it like this.
The Acer Aspire 5 has an integrated mic, so the way it works is whenever you plug into your combo jack your headphones with mic it will automatically recognize the new mic and turn off the integrated one. This is because the combo jack input is compatible with both TRS and TRRS and "tells" the difference as a consequence of physical contact (depending on what you plug in the jack which is on the motherboard, you'll get different impedance/resistance which translates to different voltages, from there the OS communicates with the drivers and has instructions on what to do depending on the readings).
If you have Windows OS you can always check if the mic has been detected by right clicking the speaker icon in the task bar/Click Sound/Click Recording. In here, simply tap your mic or make a sound and you should see these green bars.
Btw whether you have your headset plugged in or not, you'll ever see only the 1 mic device in the Recording tab (I literally just checked, and encourage you to try).