A tablespoon is a non-scientific but very widely used unit of volume, which works very well in cooking, herbal medicine, etc. It is represented by a capacity of one tablespoon which varies from roughly 15 mL in the US to 20 mL in Australia.
1 If tea is properly stored, it can potentially last up to a year for green and black teas. White tea lasts about six months before it isn't as good in quality as when fresher. Stale tea (or bad tea) will taste flat, as if you're drinking paper.  Glass or ceramic containers are fine provided that they're opaque.
It has very few to no calories or nutrients, although it does contain antioxidants. Black tea should be steeped in just boiled water. While the tea in tea bags usually has a high surface area and should only be steeped for a couple of minutes, whole leaf tea can be steeped for 5 minutes without turning bitter. Many cultures have significant rituals surrounding the brewing and serving of tea. The Health Benefits of Black Tea.