The Root chakra is about being physically there and feeling at home in situations. If it is open, you feel grounded, stable and secure. You don't unnecessarily distrust people. You feel present in the here and now and connected to your physical body. You feel you have sufficient territory.
If you tend to be fearful or nervous, your Root chakra is probably under-active. You'd easily feel unwelcome.
If this chakra is over-active, you may be very materialistic and greedy. You're probably obsessed with being secure and resist change.