Perek Shira is the song that is sung every day by all of Hashem's creations in the realms of Domem/דומם, Tzomeyach/צומח, and Chai/חיה. It is believed to have been authored by none-other than Dovid Hamelech / דוד המלך himself, who (like the Holy Ba'al Shem Tov / בעל שם טוב הקדוש) had the power to converse with animals.
Perek Shira has been likened to an orchestra with many different instruments each contributing their unique sound. Every creation sings its unique song, and when they are combined they create "beautiful music".
Man is likened to the conductor of this orchestra, without whom the music could not be elevated to its highest potential. He (man) is seen as the Crown of Creation, within whom are included all of these forces (of Domem/דומם, Tzomeyach/צומח, and Chai/חיה). Thus, when man sings Perek Shira he gives strength to All of Creation to sing their song, and when their respective ministering angels sing - they receive sustenance from above - which they in turn bring down to us.
The Ohr Hacahim Hakadosh commented (Breishit 3:1) that everything Hashem created has its own system of speech with which to praise Hashem "... and go learn this from Perek Shira".
Rebbe Levi Yitzchak of Berditchev noted that "...if a man wants one of the nations of the world to change their attitude positively towards Israel (the Jews), then if that man knows the song of the nations' angel that sings and praises Hashem, then that ministering angel has to love that man who knows his unique song to Hashem, and because he loves that Holy Jew the angel is compelled to do his will... therefore he who recites Perek Shira is great!"
Rebbe Nachman of Breslov says "Know that each shepherd has a special tune according to the grass and according to the location that the shepherd is - because all grasses have a song. This is the concept of Perek Shira. From the song of the grass a beautiful melody of the shepherd is being made".
Reciting the Perek Shira daily is a Segulah which helps in all realms: heath, well-being, financial/פרנסה, Zivug/זוג, bearing children, etc.
Reciting Perek Shira for 40 days consecutively has even more influence up above, and is said to be a tremendous Segulah, particularly for those in need of finding their bashert (spouse to be).