На афише был жёлтый фон, а название спектакля было написано серыми буквами.

На афише means on the poster / playbill.

Here афише is in the prepositional case because it comes after на in a location meaning: on, at, in.

• афиша = poster, playbill
• на афише = on the poster

This is a very common pattern:

• на столе = on the table
• на картине = in the picture / on the painting
• на афише = on the poster

So the sentence is talking about what appeared visually on the poster.

Because the verb agrees with the noun it refers to in gender and number.

In the first clause:

• фон = background, and it is masculine
• so we say был

In the second clause:

• название = title, and it is neuter
• so we say было

So:

• фон был = the background was
• название было = the title was

This is the past tense of быть and it changes by gender:

• был = masculine
• была = feminine
• было = neuter
• были = plural

Because жёлтый фон is the thing being described by был: the background was yellow.

Here фон is the subject of the clause, so it is in the nominative case. The adjective жёлтый agrees with it:

• жёлтый = masculine nominative singular
• фон = masculine nominative singular

So жёлтый фон literally means a yellow background.

In Russian, after was in this kind of descriptive sentence, Russian often uses the nominative:

• Дом был большой = The house was big
• Фон был жёлтый = The background was yellow

Here а is best understood as and, but with a slight sense of contrast or meanwhile.

The sentence is not strongly विरोधительный like English but. It is more like:

• The poster had a yellow background, and the title of the play was written in gray letters.

Russian а often connects two pieces of information that are different or contrasted in some way:

• one thing was yellow
• another thing was gray

So а highlights the contrast between the two visual details.

Very roughly:

• и = and, simply adding
• а = and / while / whereas, with contrast
• но = but, stronger contradiction

Because название usually takes the thing named in the genitive case.

So:

• название = title / name
• спектакля = of the play

Together:

• название спектакля = the title of the play

This is a common pattern in Russian:

• название книги = the title of the book
• название фильма = the title of the film
• название спектакля = the title of the play

The base form is спектакль. Its genitive singular is спектакля.

Спектакль usually means a stage performance, especially a theatrical performance. In this sentence, play is a very natural translation.

Depending on context, it can mean:

• a play
• a stage production
• a performance

So название спектакля is very naturally the title of the play.

Было написано is a passive-style construction meaning was written.

Breakdown:

• было = was
• написано = written

More literally, it is something like was in a written state.

This is built from a short passive participle:

• написан = written
• написана = written
• написано = written
• написаны = written

It agrees with the noun being described:

• название is neuter
• so we get написано

So:

• название было написано = the title was written

This is very common in Russian when talking about how something is presented:

• слово было написано крупно = the word was written large
• объявление было напечатано на бумаге = the notice was printed on paper

Серыми буквами is in the instrumental case.

Russian often uses the instrumental to show the means, manner, or form in which something is done. Here it means:

• in gray letters
• literally, something like with gray letters

So:

• буквами = letters, in the instrumental plural
• серыми = gray, agreeing with буквами

This pattern is very common:

• написано крупными буквами = written in large letters
• напечатано чёрными буквами = printed in black letters
• подписано красными чернилами = signed in red ink

So серыми буквами tells you the visual form of the writing.

Because Russian normally says something is written in letters, plural, when describing the style or appearance of writing.

So серыми буквами means in gray letters as a set of written characters.

Using the singular буквой would mean with a letter or by means of one letter, which would be a completely different idea.

Compare:

• написано большими буквами = written in big letters
• слово начинается с буквы А = the word begins with the letter A

So the plural is the natural choice here.

Russian word order is flexible, and the choice often depends on what information is being introduced first.

Starting with На афише sets the scene:

• On the poster, there was a yellow background...

This feels natural because the sentence is describing what could be seen on the poster.

If you said Жёлтый фон был на афише, it would still be grammatical, but the emphasis would be different. It would sound more like you are specifically talking about the yellow background and then saying where it was.

So the original order is very natural for visual description.

In the past tense, no: you normally need it.

So you say:

• На афише был жёлтый фон
• Название спектакля было написано серыми буквами

But in the present tense, Russian often leaves out is / are:

• На афише жёлтый фон = There is a yellow background on the poster / The poster has a yellow background
• Название написано серыми буквами = The title is written in gray letters

So English speakers often notice this difference:

• present: no is
• past: you need was

Both are good ways to understand it.

Literally, Russian is closer to:

• On the poster there was a yellow background

But in natural English, you might very well say:

• The poster had a yellow background

Russian often describes visual elements this way, using location plus was, instead of phrasing it exactly like English have.

So the structure is very normal Russian, even if English might choose a different wording.

Yes. Серыми буквами is the normal way to say that the text appeared in gray lettering.

It does not force the reader to imagine separate physical letters. It simply describes the appearance of the written title.

In good English, this is naturally:

• in gray letters
• in gray lettering
• in gray text

So the Russian phrase is idiomatic and completely normal for describing typography or design.