Idem faber scutum quoque ex ferro facit, quia milites in provincia arma volunt.

Idem means the same. Here it modifies faber: idem faber = the same craftsman / the same smith.
It’s idem because it agrees with faber, which is masculine singular nominative. (Idem is the nominative masculine singular form.)

Scutum is accusative singular, serving as the direct object of facit.
So: faber … facit scutum = the craftsman makes a shield.

Quoque means also / too. In Latin it commonly comes after the word it emphasizes.
So scutum quoque highlights that a shield too (in addition to something else) is being made.

Latin has no articles like a/the. Whether it’s a or the comes from context.
Here idem faber often implies a more specific reference (roughly the same craftsman), but Latin itself doesn’t mark articles.

Ex means out of / from (material) here. It takes the ablative case, so ferrum becomes ferro (ablative singular).
Ex ferro = out of iron / made from iron.

Sometimes Latin can use the ablative of material without a preposition (especially in poetry), but prose commonly uses ex to make the “material-from-which” idea explicit.
Ex ferro clearly signals material rather than (for example) an instrument (with iron).

Facit is present indicative active: (he) makes / is making / does make.
Whether it’s a vivid “historical present” depends on context, but by itself it’s simply present.

Quia introduces a causal clause: because…
With quia, Latin normally uses the indicative when stating a straightforward reason as a fact: milites … volunt = the soldiers want.

Milites is nominative plural, so it’s the subject of volunt in the quia-clause.
So: milites … volunt = the soldiers want…

Arma is accusative plural neuter, the direct object of volunt.
Latin commonly uses arma in the plural to mean weapons / arms as a collective set.

In with a stationary location takes the ablative, so provincia is ablative singular.
In provincia = in the province (location where the soldiers are / where the wanting is relevant).