This song has a couple examples of imagery which create the dramatic situation of the story of the song. In the first part of the song the speaker says that he/she is leaving because if he/she stays they will only be "in the way." This idea of a person being a stumbling block for foreword movement or a distraction to a present responsibility establishes the point of the whole song -- that the speaker will love the person spoken of for "always," no matter what distance or time elapses.
Another image in the next stanza is that the speaker will take with him/her the memories of their time together. This image of a person literally packing up to leave, and tucking into the suitcase some recollections of past, shared experiences is poignant and also seems kind of final -- those thoughts are being packed for good.
The speaker is leaving because it is the best and the right thing to do, but that won't change the emotion that went and continues to go into this relationship. The repetition of refrain reinforces the intensity of these emotions and serves to reassure the person being left of those feelings as well. It is a sad kind of tribute to the end of a relationship.
Below is a link to literary terms that will help you write about what the poetic device is and how it is typically used -- you can then review the song again, and see what else you can glean from it.
In 2003, Dolly Parton's "I Will Always Love You" was ranked as number 16 on the 100 Greatest Songs in Country Music. Having released it in 1974 as a tribute to Porter Wagoner, her longtime mentor and partner. Then, in 1982, Parton recorded it again for the film version of the Broadway Musical, The Best Little Whorehouse in Texas. But, the greatest success that the song has had is when it was sung by Whitney Houston in 1992.
The refrain, "I will always love" is repeated throughout, but especially at the song's end to express the continuity of feeling that will remain long after the parting. Most of the lines are in a conversational meter, with the stress upon the beginning of the line. Some lines are iambic:
Bitter sweet memories
Goodby, oh, please don't cry
Oh, I do wish you joy
But above all this
Others have different meters. For instance, "That I'll think of you every step of my way" has an unstressed syllable followed by a stressed syllable of the iambic meter.