Excluding pages and parts of the page
Pages that stay in the original language
In Translate > Tools, under Pages that stay in the original language, write one path per line. /checkout/ covers that page and everything under it; * matches anything, as in /blog/*-it/.
Words never translated
In Translate > Engine, list in Words never translated the names of the company, of products or of places, one per line. They stay exactly as written in every language.
The notranslate class
Anything with the class notranslate stays as it is, in every version of the plugin. For example: <span class="notranslate">Villa Rosa</span>.
Parts of the page by CSS selector (Pro)
With Pro, in Translate > Custom rules, under Never translate, write one CSS selector per line, such as .team-names or #price-table. Those parts stay in the original language.
Write to us and tell us which plugin, what you tried and what you see. We answer from Italy, usually within one working day.