apex-legends
When I read the amount of shields I got in Apex Legends, how can I figure out what is the 'effective HP' I currently got?
Like if a full life legend has 100 HP… how much does each segment of armor add to that pool of HP? Does one segment count as +25% max HP? +50%? Is there differences between a segment of blue armor vs a segment of purple armor?
Apex Coins 
can be purchased with real-world money, or earned as part of a purchased Battle Pass. They can be used to purchase cosmetics from the Featured section of the Store, purchase Apex Packs containing semi-random cosmetics and sometimes Crafting Materials, or unlock new Legends.
Legend Tokens 
can only be earned by leveling up (or refilling your XP bar at max level). They can be used to unlock new Legends, or purchase cosmetics in the Exclusive section of the the Store.
Crafting Metals 
are randomly included in some Apex Packs. 45 Apex Packs can by earned by reaching certain player levels, or they can be purchased with Apex Coins, or they can be earned as seasonal and Battle Pass rewards. Apex Coins can be used to directly purchase any generally-available (not exclusive or seasonal) cosmetic item in the game from the Armory and Legends screens.
They essentially reduce bonus headshot damage, with higher tiers having more of a reduction.
White: 30% Reduction
Blue: 40% Reduction
Purple/Gold: 50% Reduction
They also do no break like shields from armour does.
Best Answer
One segment of bodyshield is 25 hp. Everyone (as of season Legacy) drops with white bodyshields. This adds 50 total health. Each rarity of bodyshield adds one more segment of 25. The full breakdown is:
Base health: 100
white: +50
Blue: +75
Purple/Gold: +100
Red: +125
A bodyshield segment is the same 25 HP no matter what color the bodyshield is. A Gold bodyshield's segment only looks larger because it doesn't evo, so it is just stretched to cover the full UI of the health area.