What is Packing?
'Packing' refers to creating a bulge in your underwear, often to achieve a more masc look and feel. FTM, trans and gender variant people often pack in order to curb gender dysphoria or to better express their gender.
A 'packer' is a soft realistic penis, often made from silicone or TPE (thermoplastic elastomer) that you use to pack.
Packing is a personal decision, and it's not something that every trans / gender variant person chooses to do. It's totally up to you if it's something that makes you feel good.