Translation is only half the job
A multilingual website can easily create SEO problems if it is added as an afterthought. Language switching is not enough. Search engines need clear signals about which URL belongs to which language and market.
Localize the URL structure
Each language version should live on its own path. That makes the site easier to crawl, easier to share, and easier to understand in analytics. It also avoids the ambiguity of serving different content from the same URL.
Translate metadata, not just body copy
Titles, descriptions, Open Graph content, and structured data should reflect the same language as the page. Otherwise the user experience becomes fragmented and search results look inconsistent.
Keep slugs stable where possible
You can localize slugs if the target market benefits from it, but the rule is consistency. The content model should still know which pages are equivalents across languages so alternates can be mapped correctly.
Important nuance
Direct translation is not always the right SEO move. Search behavior varies by market, so headings and metadata should reflect local phrasing where needed.
Build with future expansion in mind
Even if the site launches in two languages, the system should be able to handle three or four later without rewriting the routing layer. Multilingual SEO becomes manageable when the structure is deliberate from day one.