How can I begin to learn Swahili? I do not know any word till now.
I didn't either but now I know it more and I just used Duolingo. It's not super challanging and really fun.
Some English loan words in Swahili: bicycle = baiskeli, pencil = penseli (if you don't use the word "kalamu", which also means pen, from Arabic qalam), machine = mashine, socks = soksi, a pump = pampu, long dress, gown = gauni, bus = basi, school = shule, coat, jacket = koti, boot = buti, week = wiki, tobacco = tumbaku (though the English is really of Indian origin, through Spanish and Arabic), cashew = korosho (though the English word comes from Portuguese through French).
— There's probably an influence from non-rhotic English pronunciation in words like these: pear = pea, dollar = dola, shirt = shati, skirt = sketi, professor = profesa.
If you know Portuguese (or Romance languages), there are some words you know like pesa (money), mvinyo (wine), karata (card), bendera (flag), buli (teapot), foronya (pillowcase), leso (handkerchief), meza (table), padri (priest), sapatu (sandles), tarumbeta (trumpet, probably from Portuguese "trombeta" rather than English), etc. Interestingly, the Swahili word gereza (prison) is supposed to have an origin in the Portuguese word for "church", igreja.
Of course, if you know Arabic or Persian, there are a HUGE number of words you know. https://baheyeldin.com/linguistics/list-of-swahili-words-of-arabic-origin.html (See comments on that page for even more.)