In 2005, Reebok began to produce Welsh ruby uniforms with the sponsorship of a beer brand. Due to the France's national anti-alcohol legislation when the team plays in France, Reebok must replace the advertising "Brains" to "Brawns".

"In 2005 the uniforms began to be produce by Reebok." First issue with this sentence is that it is passive voice (it isn't pleasant to read, but does have its place in legal and scientific writing). If you can end a sentence/clause "by zombies" and it still makes sense the sentence is passive voice (in this case you have 'by Reebok' were you'd say 'by zombies'). Despite the title, you haven't introduced the topic of Welsh ruby uniforms, and so "the" is meaningless here. The first clause needed a comma after it.

"Due to the nation anti french alcohol legislation..." This reads like the legislation is against French alcohol. Anti-X gets hyphenated usually unless it is part of the word (e.g., antibiotic). There a few ways to fix this, I prefer the method I used where the possessor (France) comes before the possessed (legislation). Though I may suggest adding if it the legislation against advertising alcohol.

"The country" is meaningless. While it is clear you mean France, you haven't established that (similar to the uniform issue above).

"You" I don't play for Wales, much less even play Rugby. Be very careful with second person and first person in English writing (especially if formal). I changed it to "the team" because we have established which team it is already (see first correction). However, I could have used "they." While everyone reading would know I logically mean the producer of the uniform, or they might think I mean Welsh ruby team (technically both work, as the team has to request the uniform change), given the structure of the sentence "they" could refer back to France's laws (though that'd be really weird) - this is very pedantic note of mine.

As for the final part " 'Brain' to 'Brawns' " - While a saying in English, and one that will fit here eventually, it currently makes no sense. You may need to elaborate on it. I didn't take a stab at what you meant in my correction because I wanted to be certain. Also remember to use the same quotation type, double or single. Don't mix, unless there is an actual reason. Also I am pretty sure that if you are changing your advertising style from direct alcohol advertising to indirect you going from 'brawns' to 'brains.' - "