Ceacht 22:
é	it	pron.	
í	it	pron.	
an __ é?	is it a __?	[part.]+...+[pron.]	
gúna	a dress	n. m4	
hata	a hat	n. m4	
cóta	a coat	n. m4	
stoca	a stocking	n. m4	
bríste	trousers	n. m4	
caipín	a cap	n. m4	
nua	new	adj.	
sean	old	adj.	
deas	nice	adj.	
go hálainn	beautiful	[part.]+[adj.# prefix#]	
go maire tú é!	may you live to wear it	[part.]+[v.]+[per. pron.]+[per. pron.]	

é is used when the subject is a masculine noun and í is used when it's a feminine noun. It is necessary in Irish to repeat the subject using either é or í depending on the gender. 

"An" This is the affirmative interrogative part of the copula and is used when one wants to ask a question involving identification. One is asking what something actually is:
 e.g. one might ask if something is a dress, a hat etc.

There is no separate word for "yes" in Irish.  The verb used in a question is repeated in the reply.  When the question contains the affirmative interrogative part of the copula "an" , a positive answer is provided by "Is ea"
In this lesson, we see for example the construction:
[copula]	+ [subject] 	+ [adjective] 	+ [pronoun]
An        	+   traein    	+    mhall      	+    í?  	(Is that a slow train?).
The subject of this sentence (traein) is a feminine noun so we use "í".

Irish adjectives normally follow the noun they qualify.

Following a feminine singular noun, the adjective is usually lenited, for example "traein mhall" (a slow train) and an adjective following a masculine noun is usually unaffected

Some adjectives require the particle go which prefixes h to those beginning with a vowel.  These adjectives tend to express a personal judgement rather than actually describing something, for example "maith" (good), "deas" (nice) and "álainn" (beautiful).  e.g."Tá tú go hálainn".

Emphatic prefix an- (very): To say that something is "very long", "very good", "very nice" etc. we use the prefix an- immediately before the adjective.  This prefix causes lenition, except where the adjective begins with d, t or s.  For example;
fada (long)			an-fhada (very long)
maith (good)			an-mhaith (very good),

but because adjectives beginning with d, t or s are not lenited, we see;
te (hot)			an-te (very hot),
deas (nice)			an-deas (very nice).