- These are characters of the Hebrew alphabet: עִבְרִית If instead you see a bunch of little boxes or question marks, then you need to install fonts with the appropriate characters
The biggest problem for incorporating Hebrew language text into the English language Wikipedia is that Hebrew flows right-to-left while English flows left-to-right. Worse, the numerals shared by the two languages don't have as strong directionality as the letters, sometimes causing seemingly inexplicable glitches, as in these example taken from the article on Ehud Olmert:
- Example of problem: Ehud Olmert (in Hebrew אולמרט) (1945 - present) is the 12th and current Prime Minister of Israel.
This can be fixed by using the Unicode left-to-right mark (LRM) U+200E at the end of the Hebrew text to signal that the following English text should be read left to right.
- Problem solved: Ehud Olmert (in Hebrew אולמרט) (1945 - present) is the 12th and current Prime Minister of Israel.
The LRM can be placed using an HTML character entity of either the hexadecimal or the decimal value:
‎. But typing these in can be very tricky: if you position the input marker just at the end of the Hebrew text – i.e., just to the left of the leftmost Hebrew character – the first non-Hebrew character you type may jump around to the right of the Hebrew even as you type the wikitext, possibly carrying more of the text with it.
In some cases it might be possible to just rephrase or move the text around so that the more strongly directioned text follows the Hebrew text. This avoids the need of the LRM altogether.
Another problem is the inconsistency in transliterating Hebrew to the Roman alphabet. The standard ISO 259 of 1984 (updated in 1994) addresses this problem by giving a one-to-one correspondence for each Hebrew letter to a Roman letter (though two options are given for ח and ש). There exists a large volume of older English literature that transliterates Hebrew differently but might be otherwise acceptable sources for Wikipedia articles on Jewish topics. Wikipedia:Naming conventions (Hebrew) has a chart with four different transliteration systems.
One suggestion is to give the word written in Hebrew the first time it appears in an article, followed immediately by one romanization, then using that romanization consistently through the rest of the article.
For Windows you can get Arial Unicode MS bundled into Microsoft Office. For macOS, the Hebrew fonts are either in /Library/Fonts or /System/Library/Fonts of the installer disc. For Linux, linux.com  provides free fonts and technical advice for keyboard mapping under X Window.