I know what watch-only address are, but I don't understand why I see these transactions.
I never imported address. The only thing I've done yesterday was to try use BarterDex.
You see the transactions because someone with the private key made transactions with them.
If the watched address is yours and you never made those transactions then your private key has been compromised.
You said you used Barterdex, which requires you to download an app on your system.
Your private key MAY have leaked when you did that
(I'm not familiar at all with Barterdex or the Komodo platform so I can't say for sure that it's the cause)