Translation:Are there yellow flowers blooming in the yard?
A very good sentence to explain word forms where the four い functions differently and these functions are common.
The sentence is read にわに (きいろい 花)が （さいて いますか) [or ... (さいて います) か].
The い in きいろ is a part of the noun いろ [colour]. Native nouns usually have readings of several kana (shorter ones like め, て [as hand] are exceptions). In this case, a single い does not make sense.
The second い is the adjective ending. Technically it is 連体形, modifying the flower.
The third い is from the special form of the 5-dan verb さく (to bloom). In classical Japanese it was さきて, and the /k/ in き was dropped and the form becomes the modern さいて.
The last い is from the auxiliary verb いる, which means 'is doing'.
On いろ. There is an (arranging) order for kana as iroha-order, which was mainly used before mid 20th century and is still being used today (though far less prevalently as the gojyuon-order). It stemmed from an ancient poem いろは歌 (いろはにほへと..., though colourful flowers bloom in a charming scent...), where all the 47 classical kana were used, and each kana used exactly once.
On 5-dan verbs. The rule is /k/ /g/ dropped (so い remained), /r/ /h/(as in 買います [which was 買ひます in the classical orthography]) /t/ to a little っ, and in the case of /n/ /b/ /m/, /i/ is dropped and the consonant is reduced to ん. In the case of /g/ and /n/ /b/ /m/, the particle て changes to で, た to だ.