"in" in french language meaning?

(1) In French as in all the Romance languages, position versus motion is shown by the verb, not the preposition, so that the word for "in" also means "into" as the word for "at" also means "to": "Je suis à la porte", "Je vais â la porte."

(2) The word for "in" in Old French was "en". Unfortunately "en le" was pronounced so like "au" (meaning "â le") that the two got confused, resulting in the crazy rule that "in(to)" is "au" before a masculine country (au Brésil, au Japon, au Portugal, aux Ètats Unis, aux Pays Bas, au Pays de Galles) but "en" before a feminine country (en Grande Bretagne, en Afrique, en France, en Provence, en Suisse...),

Otherwise "en" mostly remained in use where there was no following article: "en deshabille", "en cas", "en péril", "en ville", "en voiture", parituclary with the gerund: en parlant, en fuyant..

(2) Modern French mostly avoids the problem by using "dans" (within).