Your phone has a speaker and microphone that allows you make and answer calls handsfree. The speaker is located under the handset. The microphone is located near the bottom right of the phone's keypad.
If there are no currently connected calls to which you are talking, a call answered by pressing its appearance button is connected either handsfree or through the headset according to the phone's audio path setting.
If there is already a connected call to which you are talking handsfree, answering another call by pressing the appearance button answers that call handsfree.
Your phone is not designed as a conference room speakerphone. It is designed for use by a user located directly in front of the phone, with no obstructions between themselves and the microphone. Phones designed to be used as conference speakerphones typically have multiple microphones and are able to handle sounds coming from multiple directions. For details of conference speakerphones supported by your phone system, contact your system administrator.