what are the blinking symbols on top of characters

[td3]

right now I have a +/- symbol blinking on top of my character; Sometimes, when I get hit, other symbols appear; where can I find a list?

[td3]

I posted a video: https://imgur.com/a/UUrRINY

[Water Ｖａｐｏｒ Merchant]

That's a status indicator, likely telling you that your character is currently swimming. You can check temporary status conditions like that by checking your status effects on the character screen, the same page your mutations are on.

[Faital Ryuu]

Some of the symbols that will blink over a character are surprisingly intuitive. For example, when someone is confused, they have a flashing question mark. When someone is knocked prone or is sleeping, there's a flashing underscore. The +/- symbol you see is meant to represent wading in water. You'll see a fish symbol when you are swimming in deeper water.

Some symbols are more self-explanatory than others. Exclamation points tend to be used for multiple things like when someone is stunned or appear sometimes in fog-of-war when there is something happening out of sight.

To put the symbols together with meaning when the meaning isn't obvious, you can use (L)ook at any NPC to check their statuses.