what is “esc_html”, “esc_html ()”, “esc_html__” and “esc_html__()” in wordpress or PHP ?

“esc_html”

Filters a string cleaned and escaped for output in HTML. Text passed to esc_html() is stripped of invalid or special characters before output.

esc_html ()

Escaping for HTML blocks.

esc_html__

Retrieve the translation of $text and escapes it for safe use in HTML output. If there is no translation, or the text domain isn’t loaded, the original text is escaped and returned.

esc_html__()

Retrieve the translation of $text and escapes it for safe use in HTML output. If there is no translation, or the text domain isn’t loaded, the original text is escaped and returned.