Learn French: Il vient de sauter sur un câble sans filet ! - He just jumped on a wire without a net!

In French, the structure venir de + an infinitive verb creates the 'passé récent' (recent past). It means that an action happened very recently, translating to 'have/has just [done something]' in English.

Why isn't there an article before filet? Shouldn't it be sans un filet?

After the preposition sans (without), French normally drops indefinite articles (un, une, des) when referring to a general concept. Since he is without a net in a general sense, it is simply sans filet.

Could I use the word juste and say il a juste sauté to mean 'he just jumped'?

It is much more natural to use venir de for things that happened a moment ago. Saying il a juste sauté sounds more like 'he ONLY jumped' (meaning he didn't do anything else) rather than 'he jumped a second ago'.

Why is câble translated as 'wire' instead of 'cable'?

Câble can mean both! It refers to thick cables, wires, and even tightropes in a circus context. Here, jumping on a tightrope or thick wire without a net fits the dangerous stunt being described.