Here is the English translation of Sakal Kushal Valli (the prayer line you asked about), with the original line and a simple meaning.

Original text (transliteration from Jain scriptures): Sakala kuzalavallI, puSkarAvarta megho, durita timira bhAnu, kalpavRkSopamAna: bhavajalanidhi pota, sarva saMpattihetu, sa bhavatu satataM vaH zreyase zAMtinAtha, zreyase pArzvanAtha. Sakal Kushal Valli, Pushkaravart Megho; Durita timir Bhanu, Kalpa vriksho pamanah, Bhavajala nidhi potah, Sarva Sampatti Hetu; Sa Bhavatu Satatam Vah, Shreyase Shantinathah, Shreyase Shreyase Parshvanathah.

English translation (simple, devotional sense): All-pervading blessing of Sakal Kushal Valli: like the rain of Pushkaravarta, like the sun dispelling evil darkness, like the wish-yielding tree, like a vessel of the ocean of worldly life, like the root of all prosperity, the cause of all riches. May you be ever-present for our well-being. May Shantinath and Parshvanath be our superior guides and protectors, now and always.

Explanation (arth) in Jain context:

• This is a prayer invoking the Tirthankaras Shantinath and Parshvanath, asking for their constant blessing for welfare, victory over evils, and the attainment of prosperity.
• The phrases compare the Tirthankaras to ideal helping images: rain that nourishes, the sun that dispels darkness, a calendar-worthy wish-fulfilling tree, and a supportive ship across the sea of birth and death. They emphasize that spiritual guidance from the Tirthankaras is the source of all true prosperity.

Notes on tradition:

• The wording of prayers and their exact phrases can vary slightly between Digambar and Shwetambar manuscripts. The core meaning remains the same: reverence to the Tirthankaras and request for their constant protection and blessings for liberation and well-being.
• If you need, I can provide a Digambar-centric or Shwetambar-centric variant with any small textual differences explained.

If you’d like, tell me which tradition you’re studying (Digambar or Shwetambar) and I can tailor the explanation to that tradition.