Благо комплект сетки готов, подачу можно начинать.

Here благо is not the noun благо meaning good or benefit. It is being used as a conjunction/particle meaning something like:

• since
• as
• seeing that
• fortunately

So it introduces the reason or favorable circumstance for what follows. In this sentence, it means that because the net set is ready, the next action can begin.

This use of благо can sound a little more literary, idiomatic, or elevated than very basic connectors like потому что or так как.

This is a common Russian noun + noun structure.

• комплект = set, kit, assembly
• сетки = genitive singular of сетка

So комплект сетки literally means the set/kit of the net or the net set, depending on context.

Russian often uses the genitive case where English would use:

• of
• a compound noun
• an adjective-like noun relationship

Compare:

• стакан воды = a glass of water
• директор школы = the school director
• комплект сетки = the net set / set of the net

So сетки is in the genitive because it depends on комплект.

Готов is the short-form adjective, while готовый is the full form.

In Russian, short-form adjectives are often used:

• as the predicate in a sentence
• to describe a temporary state or condition

So:

• комплект готов = the set is ready
• готовый комплект = a ready set / a completed set

In your sentence, готов is correct because it is part of the predicate: the sentence is saying what state the set is in.

In the present tense, Russian normally omits the verb to be.

So where English says:

• The net set is ready

Russian simply says:

• Комплект сетки готов

This is completely normal. If you wanted past or future, then Russian would use forms of быть:

• Комплект сетки был готов = the net set was ready
• Комплект сетки будет готов = the net set will be ready

But in the present tense, zero copula is the norm.

Because it is the direct object of начинать.

The infinitive начинать can take an object:

• начинать что? = to start what?

Here the answer is подачу, so it goes into the accusative singular.

Basic pattern:

• начинать подачу = to start the serving / supply / feed / delivery, depending on context

Even though можно comes between the object and the infinitive, the object still belongs grammatically to начинать.

Because можно creates an impersonal construction.

Russian often uses можно to mean:

• it is possible
• it is allowed
• one can
• we can, depending on context

So подачу можно начинать literally means something like:

• the serving/supply can be started
• it is now possible to begin the serving/supply
• one can start now

This is less personal than saying:

• Мы можем начинать подачу = we can start the serving/supply

The impersonal version focuses on the situation, not on the people.

This is about verbal aspect.

• начинать = imperfective
• начать = perfective

Both can be translated as to begin / to start, but the nuance is different.

Here можно начинать suggests:

• it is now time to begin
• the process may now get underway
• the action is being viewed as the start of an ongoing process

If you said можно начать, that would sound more like:

• it is possible to start
• the single act of beginning is possible

In many contexts, both are possible, but можно начинать often feels more natural when someone is giving the go-ahead for a process to commence.

Russian word order is flexible, and changing the order often changes emphasis rather than basic meaning.

A more neutral order might be:

• Можно начинать подачу

But:

• Подачу можно начинать

puts extra focus on подачу. It can feel like:

• As for the serving/supply, that can now begin
• The serving/supply can now be started

So the object is moved forward for emphasis or topic marking.

The comma separates two clauses:

• Благо комплект сетки готов
• подачу можно начинать

The first clause gives the reason or favorable condition. The second clause gives the consequence or next step.

So the structure is roughly:

• Since/Fortunately the net set is ready, the serving/supply can begin.

The comma is natural here because благо introduces a clause that sets up the second clause.

It is understandable and normal, but it is not the most basic everyday connector.

A learner is more likely to meet and use:

• потому что = because
• так как = since/as
• раз = since, seeing that

Благо in this meaning can sound more idiomatic, somewhat literary, or stylistically marked. Native speakers do use it, but it is worth noticing that it has more flavor than a plain neutral connector.

Yes. Подача is a context-dependent noun. It can mean things like:

• a serve in sports
• a supply
• a feed
• a delivery
• a presentation or manner of presenting

So the exact interpretation depends on the wider situation. Grammatically, though, nothing changes: in this sentence it is still the accusative singular object of начинать.