The tablespoon is a unit of volume in the US customary system and uses the symbol Tbsp.
In the kitchen, the tablespoon is the larger of the commonly used spoons served at the table and represents 1/2 US fluid ounce or, expressed in SI / metric format; 14.78676 ml.
This is often expressed as equivalent to 3 teaspoons (3 Tsp) although strictly speaking it is a little under the size of 3 metric teaspoons (5 ml) at 4.92892159375 ml. It was established to assist normal kitchens with recipes without the need for specific measuring equipment or devices. Although many spoons differ in sizes (and very rarely is a spoon filled accurately) it allowed for a decent "catch-all" and gave a "good enough" result most of the time.
The US liquid pint is a unit of volume in the US customary system with the symbol pt.
1 US liquid pint is equal to 1/8 US liquid gallon. This is equal to 1/2 US liquid quart, 2 US cups, 4 US gills or 16 US fluid ounces. The SI / metric equivalent is 473.1765 ml.
From the early (1707) adoption of the British wine gallon at 231 in³, the American pint was born. Where all pints are 1/8 of their respective unit system's gallon, that put the US pint at 28.875 in³.