S Bracket Transistors and Reverse Breakdown diodes in Texas Instrument 74LS32 DataSheet?
That is an NPN transistor with integrated Baker Clamp. It can be known as a Shottky Transistor Wikipedia.



It is equivalent to this:



The diode between the collector and base prevents the transistor from saturating - if the collector attempts to go less than ~0.5V it will divert charge away from the base.

By preventing saturation the transistor can turn off more quickly because there will be less stored charge in the base region.

The diodes shown with the similar embellishment to the symbol are Shottky diodes. They are not to be confused with a zener diode that usually only have the bracket on one side, a backward diode that have them pointing the same way outwards or a tunnel diode where they both turn inwards.

Shottky diodes are diodes where one of the electrodes is a metal, rather than both being semiconductor. The turn-on voltage is significantly less and they have essentially zero stored charge so they are very fast.

The three pronged symbol is a connection to ground or in the case of an IC it is to the substrate. It also often means the connection to chassis in equipment or old schematics.