Chakras are high energy centers in your body. They regulate the energy in you, your aura and personality/feelings overall. A chakra can be closed or open. Open means it's freely flowing energy through it and very strong. Closed means it's weakened and can't take very much energy at all, it can negatively affect you in this way too. The best thing to do is to meditate on them to open them up or intentionally work on them in your every day life. You want them to be balanced with each other.
There are 7 chakras in total, each associated with a certain color and meaning.
Root Chakra (Color: Red) - This is the foundation of them all. It symbolizes being grounded and steady in yourself wherever you are. When open you are able to feel comfortable and welcome anywhere you are.
Sacral Chakra (Color: Orange) - This is about feelings and sexuality. When it's open you can freely express yourself and show intimacy and passion towards other people.
Solar Plexus (Color: Yellow) - This is about confidence and self esteem. When open you feel good asserting yourself in a group and confident in your actions.
Heart Chakra (Color: Green) - This is love, affection and kindness. When open you show compassion and can be friendly towards others, as well as work on peaceful relationships.
Throat Chakra (Color: Blue) - This is about speech and talking. When open you can freely express yourself and your ideas. It also can affect your creativity
Third Eye Chakra (Color: Purple) - This is about insight and visualization. When open it can cause you to have a higher imagination and intuition.
Crown Chakra (Color: Pink) - This is about wisdom and unity. When open you feel at one with the world and everyone in it, you are completely unprejudiced.