It's probably "stroke," as Racky says, but normally we don't use "/" in spoken English at all. Sometimes in very casual English people will say "slash," as in "He's my friend-slash-coworker," but in formal English we would only use a slash in writing, not in speech. In speech we would reword the sentence so that it doesn't contain a slash. We might say something like "between 1918 and 1919..." or "in the years 1918 and 1919..." The only exception I can think of is if you are reading a paper out loud. In that case, the speaker might read the text as "1918 slash 1919." (Saying "stoke" instead of "slash" seems strange to me, but maybe this is more common in the UK. I'm in the US.)

I think it is “stroke”.

Slash

Type it into google translate and you can hear it pronounced correctly