For the last sixty years or so, almost all cutting edge science has been published in English, and I am lucky that English is my native language. There has been some interesting work published in Russian, especially during the Cold War, but almost all of the interesting work gets translated to English within a year or two, so not reading Russian is not a big disadvantage.
However, English has not always been the dominant language of science. Before 1940 or so, the language of choice would have been German. In earlier eras, the preferred language of scientists might have been French, Latin, Arabic, or Greek.
I was reminded of this recently when my literature search on wavelets led me to the original reference on the Haar wavelet. Alfred Haar, then a professor of mathematics at Göttingen, published his paper "Zur Theorie der orthogonalen Funktionensysteme" in Mathematische Annalen (v. 69, p. 331) in 1910. This paper was, as can be guessed from the title, written in German. Our library turned out to have a copy of this volume, and so I borrowed it and tried to read it (I took three semesters of German as an undergraduate).
It really is not easy to read a technical article in a second language. Certain common words have meanings in technical usage which can differ substantially from their ordinary meanings (English and German are alike in this way). One example: stetig can be translated in ordinary usage as "constant" or "steady" (the latter word is its English cognate), but in mathematics it specifically means "continuous".
As I said, English has since displaced German as the preferred language of science. Mathematische Annalen is still published, but these days most articles are in English.
Nor is it inevitable that English will always remain the dominant language of science. The rise of science in India need not change this status quo since English is the one language that is widely spoken throughout India (it plays a similar role to that of medieval church Latin in Renaissance Europe). But China might change things--probably not in my lifetime, but maybe in the lifetime of scientists born this decade.