Un simple geste de la main et un regard gentil suffisent parfois pour rassurer un enfant.

Both are possible, but they mean slightly different things.

• un simple geste often means just a gesture / a mere gesture
• un geste simple means a simple, uncomplicated gesture

So here, putting simple before the noun adds emphasis: even something as small as a hand gesture can help.

French adjectives can sometimes change nuance depending on whether they come before or after the noun.

It literally means of the hand, but in natural English we would usually say a hand gesture.

So:

• un geste de la main = a gesture made with the hand

French often uses de + noun to specify what kind of thing it is. Here, de la main tells you what kind of gesture.

You could imagine avec la main in other contexts, but un geste de la main is the more standard expression for a hand gesture.

Because gentil agrees with regard, and regard is a masculine singular noun.

• un regard → masculine singular
• so the adjective is gentil

If the noun were feminine, the adjective would change:

• une attitude gentille

In this sentence, gentil describes the look/glance, not the child.

Yes, it is understandable and correct. It means a kind or gentle look.

That said, many native speakers might also choose words like:

• un regard doux = a gentle/soft look
• un regard bienveillant = a caring / benevolent look
• un regard tendre = a tender look

So gentil works, especially in simple everyday French, but it is a little less idiomatic than some of those alternatives.

Because the subject is made of two things joined by et:

• Un simple geste de la main
• un regard gentil

Together, they form a plural subject, so the verb must be plural:

• ... suffisent ...

If there were only one subject, it would be singular:

• Un simple geste de la main suffit parfois...

Because suffire already means to be enough / to suffice.

So:

• suffisent parfois = are sometimes enough

In natural English, we often say can sometimes be enough, but French does not need an extra verb to express that basic idea.

You could say peuvent suffire, but that would add a stronger sense of possibility or capability. The original sentence is simpler and more direct.

Pour + infinitive often means to or in order to do something.

Here:

• pour rassurer un enfant = to reassure a child

It explains the result or purpose: the gesture and the kind look are sometimes enough to reassure the child.

With suffire, French can also use à + infinitive in many cases:

• suffisent à rassurer un enfant

That is also correct. In this sentence, pour rassurer is very natural and easy to understand.

Rassurer means to reassure, to calm, or to make someone feel less worried, less afraid, or safer.

For example, if a child is upset, scared, or nervous, a kind gesture may rassurer them.

It is a very common verb in French.

Related forms include:

• être rassuré = to feel reassured
• rassurant = reassuring

French adverbs like parfois are fairly flexible, but this position is very natural.

• suffisent parfois = are sometimes enough

This is a neutral, standard placement.

You could also say:

• Parfois, un simple geste de la main...
• Un simple geste de la main... suffit parfois...

The original sentence sounds smooth and natural as written.

Here un enfant is being used in a generic sense: a child, meaning any child in that situation.

French often uses the singular indefinite article this way when speaking generally about a typical example.

So:

• un enfant = a child / any child
• les enfants = children in general
• l'enfant = the child, or sometimes the child in a more abstract/general sense depending on context

In this sentence, un enfant sounds very natural because it suggests a single child in a typical situation.

Because French normally gives each coordinated singular noun its own article when they are presented as separate items:

• Un simple geste de la main
• et un regard gentil

So the sentence clearly lists two things.

Repeating the article is standard and natural here. It helps show that the subject is made of two separate elements, which is also why the verb is plural: suffisent.