Bot= A character automated by a third party program to mine/gather/kill enemies over and over to attain large amounts of gold or materials to sell for Real Money on their illegal websites.
Grind/Mob Grinding = The act of killing the same monsters/enemies over and over to attain loot or experience points. Sometimes for hours on end, hence the "grind".
Add On = A LEGAL third party UI alteration that can be used for damage numbers, gathering node locations, and other quality of life improvements. Most of these are allowed by ZOS unless they provide some unfair advantage or alter the game. A more indepth description by ZOS can be found in their Terms you "agree" to when signing up
Normal Play = Not too sure on this one, perhaps referring to dungeons as Veteran Dungeons or Normal (low level) play dungeons. You got me on this one
Bot - or roBOT - An automated proces that controls an ingame character to do some specific things. Mostly used by leveling services or goldfarmers. They basically collect all kinds of materials to vendor, kill all types of mobs to level, or combining the two. They also have a typical and fixed behaviour pattern (always walking the same route, using the same skills and so on ..). You should report these every time you see them.
Grind- or Grinding : The process of doing the same thing over and over. You can 'grind' several things in the game. For example youi can grind crafting materials, like Iron Nodes, Jute Nodes, ....
It is tied in with Mob Grinding wich is a specific type of grinding, killing NPC's in order to level up, gain loot or gain money.
Another word for this would be farming, though there is a slight difference.
Normal play - well your guess is as good as mine with this. I think it might have something to do with the Veteran Mode (lvl 50+). Not sure though.
Add On - ADDition On the game. Eso supports the creation of little 3rd party modifications, like any Elder Scroll game before it (let's not argue ESO vs TES please). These little modifications allow you to change some aspects of the gamme, like the HUD, or Health bars , ... there are a lot of Addons. These are not made by the creators of ESO, and might stop working if the game evolves (patches & updates) when the Addon itself is not being maintained.
@Sherrieg Bots are usually identifiable by their terribly generated names examples include "aaaaflal", "kdidis", "fafafa" or other non-sensical strings of letters. They can sometimes be in very minimal gear, such as the newbie robe and a big 2 handed sword at level 15! They also usually are seen in one spot or the same spots doing the same thing over and over with no alteration to their movement path or skills used. They may also "glitch" or teleport around depending on if a hack is being used. And they will never respond to you in /whisper or /say
Grinding implies you are at your computer working away towards some goal. It may sound similar to what BOTS do, but, the biggest difference is they are being ran by programs and code, you are physically playing the game "grinding" like it was intended. Grinding is not frowned upon, unless you are a bot