Valla vs. cerca
The Spanish words 'valla' and 'cerca' are both translated as 'fence' in English, but they have different nuances and uses.
Valla
'Valla' generally refers to a billboard or a type of fence that is often made of wood or metal sheets, which is solid and not easily seen through. It can also be used for barriers in sporting events.
La valla publicitaria bloqueaba la vista del paisaje.
(The billboard blocked the view of the landscape.)
Pusieron una valla alrededor de la construcción para seguridad.
(They put up a fence around the construction site for safety.)
El corredor saltó la valla durante la carrera.
(The runner jumped over the hurdle during the race.)
Cerca
'Cerca' usually refers to a generic fence or an enclosure, typically made of materials like wire, wood, or stone. It is often used for demarcating boundaries of gardens, yards, or fields and can be see-through or have gaps between its parts.
Tenemos una cerca de madera en el jardín.
(We have a wooden fence in the garden.)
Los agricultores construyeron una cerca alrededor del campo.
(The farmers built a fence around the field.)
El perro saltó la cerca y se escapó.
(The dog jumped over the fence and ran away.)
Summary
While both 'valla' and 'cerca' can be translated as 'fence', 'valla' often implies a more solid, sometimes opaque barrier, whereas 'cerca' usually refers to more traditional fencing materials that might allow visibility through them. Choosing between them depends on the context and specific type of barrier being referred to.