Если долго лежать на солнце без крема, можно обгореть, и тогда никакой загар не радует.

This sentence uses an impersonal, general-condition pattern:

Если долго лежать на солнце без крема, можно обгореть.

It means something like If you lie in the sun for a long time without sunscreen, you can get sunburned, but in a more general one/people/you in general sense.

Russian often uses the infinitive this way when giving a general warning, rule, or observation. A version like Если долго лежишь... is possible too, but it sounds more directly addressed to you.

Можно is an impersonal word meaning it is possible, one can, or sometimes you can.

So:

можно обгореть = you can get sunburned / it’s possible to get sunburned

It does not mean permission here. It is about possibility/consequence, not allowed to.

Обгореть is perfective, so it focuses on the result: ending up sunburned.

In this sentence, the point is the consequence of lying in the sun too long:

можно обгореть = you can end up getting burned

If you used обгорать instead, it would sound more like a process or repeated tendency, which is less natural here.

After на, when Russian expresses location, it usually takes the prepositional case.

So:

• солнце → на солнце

The phrase лежать на солнце is the normal idiomatic way to say to lie in the sun.

Even though English says in the sun, Russian uses на солнце.

The preposition без always takes the genitive case.

So:

• крем → без крема

That is why you get без крема.

In this context, крем usually means sun cream / sunscreen, even though the word by itself can just mean cream.

Yes, the subject is not stated explicitly because the sentence is meant to be general.

Russian often leaves out you, one, or people when the meaning is obvious from context. So the sense is:

• If you / one / people lie in the sun too long without sunscreen, you can get sunburned

This kind of impersonal wording is very common in Russian.

Никакой means no, not any, or no kind of.

So:

никакой загар не радует literally means something like no tan makes you happy or then no tan is enjoyable at all.

It adds emphasis. The idea is: after getting badly sunburned, the idea of a tan is no longer pleasing.

Because загар is the subject of радует, so it stays in the nominative case:

• никакой загар не радует

A very common learner mistake is to expect genitive after negation everywhere, but negation does not automatically force genitive in all positions. Here, загар is not a direct object; it is the thing that does not please.

So nominative is correct.

Because the subject is singular:

• загар = tan
• никакой загар = no tan

So the verb is singular too:

• никакой загар не радует

If the subject were plural, the verb would be plural as well.

Russian often omits the person affected when it is understood from context.

So никакой загар не радует really means something like:

• no tan makes you happy
• no tan is pleasing anymore
• then you’re not happy about any tan

A fuller version could include an object such as тебя, but Russian does not need to say it here.

Russian often uses the present tense of the imperfective to express a general truth or a typical reaction.

So:

тогда никакой загар не радует means something like then no tan is enjoyable / then no tan makes you happy

It is not about one exact moment only. It describes what is generally the case once that situation happens.

Тогда means then or in that case.

It connects the consequence more clearly:

• first: можно обгореть
• then: никакой загар не радует

So it marks the next logical step: if you get sunburned, then a tan stops being enjoyable.

There are two main reasons:

1. Если долго лежать на солнце без крема is a subordinate conditional clause, so it is separated by a comma from the main clause.
2. The sentence then joins another clause with и, and that second clause has its own predicate: никакой загар не радует.

So the punctuation reflects the structure:

• conditional part
• main result
• added consequence

That is why the commas are natural and expected here.