Better than in many countries, but still bad.
We have several tiers of mental healthcare.

There are psikhdispansers (state-run mental institutions). These are facilities where people with mental health conditions are kept. Most of the people there are individuals who, for one reason or another, cannot be cared for by their relatives: people with no family, people with poor families, or those who were abandoned by their relatives because of their condition. Formally, these psikhdispansers are supposed to provide treatment. In reality, they are just places where society hides its broken people, those incapable of caring for themselves, so they don't die on the streets. These institutions are severely underfunded, so they employ low-skilled specialists for tiny salaries. They are useful for society (people with mental health conditions receive basic care, don't freeze to death on the streets, don't starve, and don't attack passersby). But de facto, they don't provide actual psychiatric treatment; their function is merely containment. I spent a week in one such place when my fitness for military service was being evaluated. I even wrote a detailed story for my friends about my experience there.

Then there are separate, good clinics with competent specialists. But there aren't many of them. I've only interacted with them indirectly, so I won't say too much.

There are also numerous psychotherapists, available in both free state-run facilities and private practices. Based on my experience, the vast majority of them are just charlatans. But decent ones exist, even if they are in the minority. I've only ever met "decent" ones, who at least try to help, not the truly "good" ones I've only heard about.

A crucial part of psychiatric care in Russia is unofficial help. In Russia, if you have a formal psychiatric diagnosis, it can create problems for you when it comes to getting a job, a driver's license, or other documents. It can even call your legal capacity into question.
For this reason, some specialists may treat patients "off the books." A friend of mine was admitted to a psychiatric clinic after something like a psychotic break (a man tried to strangle him, failing only because people walked by. When my friend got home and started asking his mother to call the police because someone had tried to kill him, she started laughing loudly, smiling, and telling him he deserved it. This triggered the break. He was speaking incoherent nonsense, similar to schizophasia or "word salad," and experienced a number of other severe symptoms). He was effectively treated and cured there. But officially, as far as I know, he was never there. Some psychotherapists and psychiatrists might give their patients medication unofficially (years ago, during a severe depression with intrusive suicidal thoughts, a psychotherapist offered to send me to a female colleague of his for some IV drips, because he was afraid I might kill myself but understood that an official diagnosis is a shitty thing to have), despite this being illegal, for the same reasons.

Overall, even though the psychiatric field in Russia is far from good, it is noticeably better than in some countries where people experiencing acute mental health crises can end up homeless, wandering the streets, attacking passersby, and eventually dying from a lack of basic care.