Problem with brake rod end

[Quixy]

So recently I noticed that my rear brake rod was very loose and I tried to tighten it up using barrel adjuster. Then I saw that it won´t work and the end of the rod looked like it had worn off or just got broken. I hope to get some help from here, because I really don´t know what to do except taking my bike to maintenance. Thanks for helpers!

That´s how it should be (front brake):
That´s how it is (rear brake):

[DaveM]

Yes, there is a problem with the brake "cable" for your rear brake. The barrel shaped piece on the end of the cable is not correctly seated into the holder on the brake lever (the silver part with the round hole). You should assume that this brake will fail at any time, so you would want to find a fix right away. It's not normal for the barrel end to slip out like that under normal use, so it may be that the holder is bent or there is another issue. If you look up videos for "how to change a brake cable" you should get something that shows you how the parts fit together. But try to figure out if there is something damaged. You don't want to assume all is well on brakes and then find out the hard way there was something broken.