scheinen
to shine
To emit or reflect light.
Die Sonne scheint heute den ganzen Tag.
The sun is shining all day today.

to shine / seem
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to shine
To emit or reflect light.
Die Sonne scheint heute den ganzen Tag.
The sun is shining all day today.

The two meanings can be distinguished well by sentence structure. If the subject is a source of light (sun, lamp), 'scheinen' means to give off light. If it is combined with 'zu' + infinitive or an adjective, it means 'den Anschein haben' (to seem).
Der Mond scheint heute Nacht sehr hell.
The moon is shining very brightly tonight.
In the meaning 'den Anschein haben' (to seem), 'scheinen' is often used like a modal verb and appears together with 'zu' and an infinitive at the end of the sentence. This construction expresses an assumption.
Der Chef scheint mit dem Ergebnis zufrieden zu sein.
The boss seems to be satisfied with the result.
When 'scheinen' describes the emission of light, the typical subjects are sources of light. These include especially 'die Sonne' (the sun), 'der Mond' (the moon), 'die Sterne' (the stars), or artificial light sources like 'die Lampe' (the lamp) or 'die Taschenlampe' (the flashlight).
Die Sterne scheinen klar am Nachthimmel.
The stars are shining clearly in the night sky.
to sound
'scheinen' and 'klingen' can both express what impression something makes. 'scheinen' is more general: something appears to be true, even if you do not know for sure. 'klingen' is used especially when the impression comes from words, a voice, music, or a sound. The words can be confused because both can express an assumption. If you see something or are judging a situation in general, 'scheinen' often fits. If you hear something or are paying attention to the wording, 'klingen' is more natural.

Der Plan scheint gut zu sein, aber wir müssen ihn noch prüfen.
The plan seems to be good, but we still need to check it.
Deine Nachricht klingt freundlich, aber auch ein bisschen unsicher.
Your message sounds friendly, but also a little unsure.