Había un pétalo rojo en el suelo y otra espina junto a la rosa.

Había is the imperfect form of haber used in the existential sense, meaning there was or there were.

So:

• Hay = there is / there are
• Había = there was / there were

The imperfect is common when you are describing a scene, giving background information, or saying what was present in a place.

Here, the sentence is basically setting the scene: a red petal was on the ground, and another thorn was next to the rose.

Because this is existential haber, which is impersonal in standard Spanish. That means it stays in the third person singular, even if what follows is plural or if there is more than one thing.

So Spanish says:

• Había un pétalo rojo...
• Había dos pétalos...
• Había un pétalo rojo y otra espina...

Not standard: habían in this kind of sentence.

This is one of the most important rules with haber meaning there is/there are.

Usually, había is the better choice here.

The difference is:

• había = there was / there were; it introduces the existence of something
• estaba / estaban = was / were; it talks about the location or state of something already identified

Compare:

• Había un pétalo rojo en el suelo.
  = There was a red petal on the ground.

• El pétalo rojo estaba en el suelo.
  = The red petal was on the ground.

So había sounds natural when you are presenting the items as part of the scene for the first time.

In Spanish, otro/otra normally replaces the indefinite article.

So you say:

• un pétalo
• una espina
• otro pétalo
• otra espina

Not normally:

• una otra espina

So otra espina is the normal way to say another thorn or a different thorn.

This is a good question. Otro/otra can mean:

• another
• one more
• a different

It does not always require that the exact same noun was already mentioned in the previous words. Here, otra espina suggests an additional item in the scene.

So the sentence presents:

• one thing: un pétalo rojo
• another thing: otra espina

In very neutral wording, una espina could also be possible, but otra espina adds the sense of one more element in the picture.

Because espina is a feminine noun, so the determiner has to agree with it.

• el pétalo → masculine
• la espina → feminine

That gives:

• otro pétalo
• otra espina

Spanish words that go with the noun usually have to match its gender and number.

Because in Spanish, adjectives usually come after the noun.

So:

• un pétalo rojo
• una rosa blanca
• una espina pequeña

Putting rojo before the noun would sound unusual here and could feel poetic, literary, or emphatic rather than neutral everyday Spanish.

So pétalo rojo is the normal word order.

Junto a means next to, beside, or close to.

In this sentence:

• junto a la rosa = next to the rose

It suggests proximity, not necessarily physical contact, though it can be very close.

A common alternative is:

• al lado de la rosa = beside / next to the rose

Both are natural. Junto a is slightly more compact and a bit more formal/literary in feel than al lado de, but both are very common.

Using la rosa makes the rose sound specific or already identifiable in the context.

Spanish often uses the definite article more than English does. So la rosa can mean:

• the rose
• the rose that is obvious in the situation
• the rose already known in the scene

If you said una rosa, it would introduce it as just a rose, not a specific one.

So the choice between la and una depends on whether the noun is being treated as known/specific or new/indefinite.

Suelo can mean both floor and ground, depending on context.

So:

• indoors, en el suelo often means on the floor
• outdoors, it can mean on the ground

In this sentence, with a petal and a rose, English might naturally say on the ground, but suelo is still a very normal Spanish word.

Also, Spanish normally uses the article here:

• en el suelo = on the ground / on the floor

not usually just en suelo.

Había is pronounced roughly ah-BEE-ah.

The accent mark on í shows that the stress falls on that syllable:

• ha-bí-a

It also helps show that í and a are pronounced in separate syllables, not merged together.

So:

• había = ha-bí-a

The written accent is important because it tells you both the stress and the syllable pattern.

Yes. It is always best to learn Spanish nouns together with their article:

• el pétalo
• la espina
• la rosa
• el suelo

That helps you automatically choose the right forms later:

• un pétalo rojo
• otra espina
• la rosa

Even though many noun endings give clues, the safest habit is to memorize the noun with el or la.