The use of "Lo" in the following sentence...

[Tycholiz]

"Eso no es lo que acordamos."

I don't understand why this is used here. It seems to work without it. Any explanations are greatly appreciated. thanks!

[AngelicaDeAlquezar]

No, it doesn't work without the article "lo".
"Esto es que acordamos" would sound very awkward and rather fragmentary.

"Lo que" together, make a neuter relative pronoun which, here, plays the role of the content of the agreement.

· Dijimos que repartiríamos el pastel en mitades, pero te comiste dos tercios; eso no es lo que acordamos.
We said that we would share the cake half and half, but you ate two thirds; that's not what we agreed.

· Este es tu dinero del negocio; cincuenta por ciento, que es lo que acordamos.
This is your money from the business; 50%, which is what we agreed.

[aleCcowaN]

It doesn't work at all without that lo.

eso que acordamos = that thing
lo que acordamos = the thing
eso no es lo que acordamos = that's not the thing

[Tycholiz]

I appreciate the responses but still do not understand when to use it. Could anyone else offer some kind of explanation? Thanks

[Rusty]

Anytime you would say "what" in English and it's underlying meaning is "that which" or "the thing that" is when you would use "lo que" in Spanish.

Eso no es lo que acordamos.
Eso = that (referring to something already stated)
no es = isn't
lo que = what = that which | the thing that
acordamos = we agreed (upon)

No entendí lo que dijo.
no entendí = I didn't understand
lo que = what = that which | the thing that
dijo = he/she/you said

[Tycholiz]

perfectly understood. Thanks a lot for the explanation!

[Rusty]

You're welcome!