What is the meaning of ヲ?

The katakana syllable ヲ (wo). Its equivalent in hiragana is を (wo). It is the forty-seventh syllable in the gojūon order; its position is ワ行オ段 (wa-gyō o-dan, “row wa, section o”).

The katakana syllable ヲ (o). Its equivalent in hiragana is を (o). It is the forty-seventh syllable in the gojūon order; its position is ワ行オ段 (wa-gyō o-dan, “row wa, section o”).

Source: wiktionary.org