Pedimos ayuda y nos echaron una mano.

Both are in the pretérito (the simple past), which is the tense Spanish usually uses for completed actions in the past.

• pedimos = we asked
• echaron = they gave / they lent in this idiomatic expression

In this sentence, the speaker is talking about two finished events:

1. We asked for help
2. They gave us a hand

So the preterite is the natural choice.

Spanish forms can sometimes look the same in different tenses. Pedimos can be:

• present: we ask
• preterite: we asked

You know which one it is from the context. Since the second verb is clearly past (echaron = they gave), pedimos is also understood as past here.

So in this sentence, pedimos ayuda means we asked for help, not we ask for help.

Spanish often leaves out subject pronouns because the verb ending already tells you who the subject is.

• pedimos already tells you the subject is we
• echaron already tells you the subject is they

So:

• Pedimos ayuda = We asked for help
• Nos echaron una mano = They gave us a hand

You could add pronouns for emphasis or contrast:

• Nosotros pedimos ayuda
• Ellos nos echaron una mano

But in normal Spanish, they are usually omitted.

Echar una mano is an idiomatic expression meaning:

• to give someone a hand
• to help

Literally, it looks like to throw a hand, but that is not what it means in real usage.

So:

• Nos echaron una mano = They gave us a hand / They helped us

It is a very common and natural expression.

Because object pronouns like me, te, nos, os, lo, la, les usually go before a conjugated verb.

So:

• nos echaron una mano = correct
• echaron nos una mano = incorrect

This is the normal position with a finite verb.

You would attach the pronoun only in certain structures, such as:

• echarnos una mano = to give us a hand
• echándonos una mano = giving us a hand
• échennos una mano = give us a hand (command form)

But with echaron, the pronoun goes before the verb: nos echaron.

Nos is the indirect object pronoun here, meaning to us.

So:

• Nos echaron una mano literally works like They gave a hand to us
• Natural English: They gave us a hand / They helped us

It tells you who received the help.

After verbs like pedir, Spanish often uses a noun without an article when speaking in a general sense.

So:

• pedir ayuda = to ask for help
• pedir dinero = to ask for money
• pedir permiso = to ask for permission

Using la ayuda would usually sound more specific, as if you mean the help in a particular, already known sense. In this sentence, the general idea is simply we asked for help, so ayuda without an article is the natural choice.

Not specifically. Echaron means they gave or they helped, but the sentence does not identify exactly who they are.

Spanish often leaves the subject implicit when it is:

• obvious from context
• unknown
• not important
• already mentioned earlier

So nos echaron una mano just means someone / some people helped us, with they understood from the verb ending.

Because echar una mano is a fixed expression. The idiom normally uses singular:

• echar una mano = to help / to give a hand

Even if several people helped, the expression often stays singular:

• Nos echaron una mano

You may also hear echar una mano used broadly without focusing on the number of helpers. The idiom is more important than the literal image.

Yes. Pedimos ayuda y nos ayudaron is grammatically correct and means basically the same thing:

• We asked for help and they helped us

But nos echaron una mano sounds a bit more idiomatic, colloquial, and natural in everyday speech.

So the difference is mostly one of style:

• nos ayudaron = direct and neutral
• nos echaron una mano = more idiomatic, friendly, conversational

Y simply means and. It links the two completed actions:

• Pedimos ayuda = We asked for help
• y nos echaron una mano = and they gave us a hand

So the structure is very straightforward:

action 1 + y + action 2

It shows that one event happened and then another followed.

Yes, it is very common in Spain and sounds very natural in everyday Spanish there.

In Spain, you will often hear things like:

• ¿Me echas una mano? = Can you give me a hand?
• Te echo una mano = I’ll help you
• Nos echaron una mano = They helped us

Learners should recognize it as a very useful everyday expression, especially in informal and neutral spoken Spanish.