Salaam. Bismillah Al Rahman Al Raheem.
Hijab encompasses the intent, the mind, the action (guarding ones chastity from those you are unmarried to, talking, walking, interacting, spending) and the clothing, for both men and women.
Allah commands Women to wear a specific clothing which is the Khimar (Surah Noor ayat 30), a long head veil covering your chest (bosom), and the Jalabiya (Surah Ahzab ayat 59) which is a long loose dress.
Allah Al Rahman Al Raheem also commands that women walk in a soft straight manner so that there female parts do not shake and become apparent. Women are also commanded to hide adornments which Allah adorned us with, breasts, hair, buttocks, legs, the womans curves. Hijab also means no embellishments such as fancy clothing and jewelry and heels, fancy watches and rings, and such, for men and women. Not only are such embellishments against hijab but it is not Humble of us to wear in the presence of others then our family. First because of beauty, lust, pride, envy, attention, and second because those with less money will feel bad.
We should be simple folk like our RasoolAllah may peace and blessings be upon him and those he loves.
Hijab is also restraint from lower urges and desires, for both men and women.
These answers although I have given them can be found in the Glorious Qur'an. All answers can be found in Allah AlRahman AlRaheems Words.