I am having trouble reading “Pero” because the translation on Lingq has the meanings of “but, yet, however” and “Su” has the meanings of “his, her; their; your, it’s” because these words have multiple means it is difficult to read Spanish text because I do not know which meaning to use for each word?
How does everyone else with a high level of Spanish deal with these words?
Gracias.
Basically I just use context. If a text is talking about a person then uses “su,” you can infer that it is talking about that person’s belonging. Also, if you are talking to someone formally, “su” is the possessive form of “usted,” the formal “tu.” This means if I were talking to my boss or my elder about his/her belonging, I would use “su.”
“Pero” basically can always be translated to “but” and it will make sense.
ah muchas gracias amigo!
Agreed.
Mr. President, is this SU White House?
Si, it’s MI White House.
Julio, is this TU lawn mower? Or does it belong to Hector?
It is SU lawn mower. He uses it to mow SU lawn.
ALSO:
pero = but
sino = but rather (contrasting after a negative eg. Australia is not in the northern hemisphere, but rather is in the southern one)
sino que = sino followed by a conjugated verb.
And use “Sin embargo” for “However,…” and use todavia (accent on i) and or aun with an accent on the u for for “yet.”
Okay great I am gonna change the translation on lingq - Pero = But and “su” into = your?
“Pero” does mean “but.” However, as LILingquist stated, you should keep in mind that there are ALSO other ways to say “but” – for example, “sino” is used when one is contrasting something. You need not learn the other ways now, but when you encounter them in more complex texts and translate them, do NOT think that you can substitute “sino” with “pero.” You will need to learn when each is used.
You should definitely NOT translate “su” as “your” precisely because it does have several meanings – his, her, your (formal), their, and its. (Note that the latter is the neuter possessive form and does NOT have an apostrophe. “It’s” is a contraction that means “it is.” Contrast “it’s raining outside” with “the dog’s fur is fluffy but its tail is short.”) While as a beginner, you may want to have a single word translation of the Spanish “su,” you nevertheless have to learn that the meaning depends on the context. In English, we have the word “read” which can either refer to the present tense (the children read the book in class) OR the past tense (the children read the book yesterday). Note that the word is spelled the same but pronounced differently too! English speakers understand the context and have no problem distinguishing them. Context matters and that’s one of the things that yes, you have to learn when learning another language. 
La muchacha se sienta con su perro (her dog).
El hombre se sienta con su amigo (his friend)
Los estudiantes se sientan con su profesor (their teacher)
el gubierno cambia su política (its policy))
Señor García, gracias por su ayuda (Mr. García, thank you for your (formal) help.)
Mama, gracias por tu ayuda (Mom, thanks for your (familiar) help.)
As has been said, “pero” = “but”, simple enough.
As for “su”, you can translate it as "that person’s " (or “that thing’s” in some cases). This is the usual waty to express his/her/its/their in Spanish. You can precise more “de él / de ella / de ellos” but we only do so when necessary.
Plus, realize that in Spanish you can address a person or group of persons in a polite way, which corresponds to talking with him/her as if it were a third person (only you’d use “usted” rather than he/she). That’s why “su” can also sometimes mean “your” (although the proper word for “your” is “tu”). Don’t worry too much about this variant. Usually there would be some further clarification in this particular usage “su/la casa de usted/es”, etc.
If you want a single translation, think su = that person’s and you’ll be fine. Remember also that “su” is a short form, used in front of nouns, the full form is suyo/suya (his/hers/its/theirs)