Hi, In this case, the grammatically correct form is “two feet” and without the hyphen. Additionally, for measuring height, we usually say “tall” instead of “high.” I also want to point out that you will definitely see the phrase “two-foot” being used in English. However, it will only take place as an adjective in the sentence. Nouns in English can become “modifiers” which act as adjectives. When they do, these nouns usually only take on their singular form. The word “foot” becomes a modifier if your sentence is changed to: “The two-foot tall bird stands in the sun.” Hence, we say “two-foot” instead of “two-feet.” Other examples of modifiers include the word “face” in “face masks.” Notice how it’s “face masks” and not “faces masks.” In summary, you can write your sentence in two ways: 1. [A] bird about two feet [tall] stands in the sun. 2. [A] two-foot [tall] bird stands in the sun.