Most two way radios have a jack for a two-way radio audio accessory like a headset or speaker microphone. When headsets are used with VOX capability the user can talk with hands free operation.
There are a variety of audio accessories available for two-way radios depending on your application. If you want to wear your radio on your belt, but do not want to be constantly taking it off to talk, then a speaker microphone with a clip that lets you mount it near your ear may be what you want. Having the speaker near your ear is great for noisy environments. You see police officers using these. Of course their shirts or jackets have a special place to clip the speaker mic on their shoulder so this may not work for a person wearing average clothes.
If you would rather be more like the Secret Service than the police, you can get a security type earpiece with a pendant push-to-talk switch with built-in microphone and clip. You put the earphone in your ear and clip the microphone/switch to your clothes not too far from your mouth and then you just push the switch when you want to talk.
If you don't want to have the curly cord leading up to the earpiece, you can get a headset that has an earbud that looks more like what you would find on an iPod or iPhone. It still has a pendant push-to-talk switch with built-in microphone and clip.
You can also get a single-ear lightweight behind-the-head headset with boom microphone and pendant push-to-talk switch. This is more like what you would see a telephone call center agent wear. This one is great for noisy environments and is comfortable enough to wear for long periods.
If you purchase a base-station intercom to use with your two way radios you may want to add an external speaker if you are using it in a noisy environment. You'll get a little extra volume out of the unit, plus they come with a longer cord so you can place the speaker somewhere closer to where you will be when you are not talking on the intercom.